論文リスト

@article{s24248162c,

title = {Free-Space to SMF Integration and Green to C-Band Conversion Based on PPLN},

author = {Takahiro Kodama and Kiichiro Kuwahara and Ayumu Kariya and Rikizo Ikuta},

url = {https://www.mdpi.com/1424-8220/24/24/8162},

doi = {10.3390/s24248162},

issn = {1424-8220},

year  = {2024},

date = {2024-12-21},

urldate = {2024-12-21},

journal = {Sensors},

volume = {24},

number = {8162},

abstract = {In this study, we experimentally demonstrate a PPLN-based free-space to SMF (single-mode fiber) conversion system capable of efficient long-wavelength down-conversion from 518 nm, optimized for minimal loss in highly turbid water, to 1540 nm, which is ideal for low-loss transmission in standard SMF. Leveraging the nonlinear optical properties of periodically poled lithium niobate (PPLN), we achieve a wavelength conversion efficiency of 1.6% through difference frequency generation while maintaining a received optical signal-to-noise ratio of 10.4 dB. Our findings underscore the potential of integrating PPLN-based wavelength conversion with fiber optic networks, offering a viable solution for next-generation optical sensor systems that demand real-time, low-latency, and reliable data transmission. This work represents a significant advancement in developing robust and efficient optical sensor technologies, addressing the challenges associated with long-distance transmission and broad-linewidth light sources in optical remote sensing applications.},

keywords = {quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{OE533201,

title = {Frequency stabilization via interference between transmitted and reflected lights from a reference cavity},

author = {Rikizo Ikuta },

doi = {10.1364/OE.533201},

year  = {2024},

date = {2024-08-29},

urldate = {2024-08-29},

journal = {Optics Express},

volume = {32},

issue = {19},

pages = {33042-33052},

keywords = {linear optics, optical cavity},

pubstate = {published},

tppubtype = {article}

}

@article{PRR5043167,

title = {Designing nontrivial one-dimensional Floquet topological phases using a spin-1/2 double-kicked rotor},

author = {Yusuke Koyama and Kazuya Fujimoto and Shuta Nakajima and Yuki Kawaguchi},

url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.043167},

doi = {https://doi.org/10.1103/PhysRevResearch.5.043167},

year  = {2023},

date = {2023-11-22},

urldate = {2023-11-22},

journal = {Phys. Rev. Research},

volume = {5},

issue = {4},

pages = {043167},

keywords = {atom},

pubstate = {published},

tppubtype = {article}

}

@article{OE494313,

title = {Quantum frequency conversion using 4-port fiber-pigtailed PPLN module},

author = {Shoichi Murakami and Rintaro Fujimoto and Toshiki Kobayashi and Rikizo Ikuta and Asuka Inoue and Takeshi Umeki and Shigehito Miki and Fumihiro China and Hirotaka Terai and Ryoichi Kasahara and Tetsuya Mukai and Nobuyuki Imoto and Takashi Yamamoto },

doi = {10.1364/OE.494313},

year  = {2023},

date = {2023-08-17},

urldate = {2023-08-17},

journal = {Optics Express},

volume = {31},

issue = {18},

pages = {29271-29279},

keywords = {entanglement, quantum frequency conversion, quantum internet},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.108.012612,

title = {Efficient Dicke-state distribution in a network of lossy channels},

author = {Wojciech Roga and Rikizo Ikuta and Tomoyuki Horikiri and Masahiro Takeoka},

url = {https://link.aps.org/doi/10.1103/PhysRevA.108.012612},

doi = {10.1103/PhysRevA.108.012612},

year  = {2023},

date = {2023-07-12},

urldate = {2023-07-01},

journal = {Phys. Rev. A},

volume = {108},

issue = {1},

pages = {012612},

publisher = {American Physical Society},

keywords = {entanglement, quantum internet, quantum repeater},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.130.200602,

title = {Linear Optical Quantum Computation with Frequency-Comb Qubits and Passive Devices},

author = {Tomohiro Yamazaki and Tomoaki Arizono and Toshiki Kobayashi and Rikizo Ikuta and Takashi Yamamoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.130.200602},

doi = {10.1103/PhysRevLett.130.200602},

year  = {2023},

date = {2023-05-19},

urldate = {2023-05-19},

journal = {Phys. Rev. Lett.},

volume = {130},

issue = {20},

pages = {200602},

publisher = {American Physical Society},

keywords = {linear optics, quantum computation, quantum frequency comb},

pubstate = {published},

tppubtype = {article}

}

@article{Tsujimoto:23,

title = {Quantum State Tomography of Qudits via Hong-Ou-Mandel Interference},

author = {Yoshiaki Tsujimoto and Rikizo Ikuta and Kentaro Wakui and Toshiki Kobayashi and Mikio Fujiwara},

url = {https://link.aps.org/doi/10.1103/PhysRevApplied.19.014008},

doi = {10.1103/PhysRevApplied.19.014008},

year  = {2023},

date = {2023-01-04},

urldate = {2023-01-01},

journal = {Physical Review Applied},

volume = {19},

issue = {1},

pages = {014008},

publisher = {American Physical Society},

abstract = {We propose a method to perform the quantum state tomography (QST) of an n-partite qudit state embedded in single photons based on the Hong-Ou-Mandel interference between the target photon and ancillary probe light. Our method requires only passive beam splitters in the target modes by shifting all of the active devices used in conventional QST methods to the probe preparation system. This feature is useful when the active optical devices for QST have large optical losses. Moreover, even when the probe is prepared by a laser light having a mode mismatch with the target photon, the method offers an accurate estimation of the target state. As a proof-of-principle, we perform the experimental demonstration using a polarization qubit. Regardless of the photon statistics of the probe light, the estimated results of state reconstruction are as accurate as those verified by the conventional QST.},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta:22,

title = {Wave-particle duality of light appearing in an intensity interferometric scenario},

author = {Rikizo Ikuta},

url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-30-26-46972},

doi = {10.1364/OE.474766},

year  = {2022},

date = {2022-12-09},

urldate = {2022-12-09},

journal = {Optics Express},

volume = {30},

number = {26},

pages = {46972--46981},

publisher = {Optica Publishing Group},

abstract = {A single photon exhibits wave-particle duality in the Young’s double-slit interferometer. The duality characterized by an interference visibility and a which-path information has trade-off relation known as complementarity. These quantities are related to the first-order coherence, and the interference is based on the phase correlation between lights coming from two arms. However according to quantum optics theory, such a simple wave-particle picture is not enough to understand the nature because the theory showed an importance of higher-order coherence in the sense of both interference and statistical distribution of photons. Second-order intensity correlation is especially crucial to reveal distinctive quantum features of photons with no classical analogue. Here, in an intensity interferometric scenario as represented by the Hong-Ou-Mandel interferometer, we discuss a wave-particle duality of light based on a which-path information and a quantity characterizing a magnitude of the intensity interferometric effect. We show, for classical light, the two quantities obey the complementary principle similar to the case of the double-slit experiment, but do not for nonclassical light. The nonclassical light such as photons at two arms is allowed to show larger which-path information and intensity interference simultaneously beyond the complementary relation. Moreover, the violation reveals a new nonclassical nature of light although both of the above two quantities seem to be understandable classically, which is never found from a consideration of only one side of wave-particle duality.},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{Fujimoto:22,

title = {Entanglement distribution using a biphoton frequency comb compatible with DWDM technology},

author = {Rintaro Fujimoto and Tomohiro Yamazaki and Toshiki Kobayashi and Shigehito Miki and Fumihiro China and Hirotaka Terai and Rikizo Ikuta and Takashi Yamamoto},

url = {http://opg.optica.org/oe/abstract.cfm?URI=oe-30-20-36711},

doi = {10.1364/OE.469344},

year  = {2022},

date = {2022-09-01},

urldate = {2022-09-01},

journal = {Optics Express},

volume = {30},

number = {20},

pages = {36711--36716},

publisher = {Optica Publishing Group},

abstract = {We demonstrate a distribution of frequency-multiplexed polarization-entangled photon pairs over 16 frequency channels using demultiplexers for the signal and idler photons with a frequency spacing of 25 GHz, which is compatible with dense wavelength division multiplexing (DWDM) technology. Unlike conventional frequency-multiplexed photon-pair distribution by a broadband spontaneous parametric down-conversion (SPDC) process, we use photon pairs produced as a biphoton frequency comb by SPDC inside a cavity where one of the paired photons is confined. Owing to the free spectral range of 12.5 GHz and the finesse of over 10 of the cavity, the generated photons having a narrow linewidth in one channel are separated well from those in the other channels, which minimizes channel cross-talk in advance. The observed fidelities of the photon pairs range from 81 % to 96 % in the 16 channels. The results show the usefulness of the polarization-entangled biphoton frequency comb for frequency-multiplexed entanglement distribution via a DWDM system.},

keywords = {entanglement, optical cavity, quantum frequency comb, quantum internet},

pubstate = {published},

tppubtype = {article}

}

@article{Yamazaki2022,

title = {Massive-mode polarization entangled biphoton frequency comb},

author = {Tomohiro Yamazaki and Rikizo Ikuta and Toshiki Kobayashi and Shigehito Miki and Fumihiro China and Hirotaka Terai and Nobuyuki Imoto and Takashi Yamamoto},

url = {https://www.nature.com/articles/s41598-022-12691-7},

doi = {https://doi.org/10.1038/s41598-022-12691-7},

year  = {2022},

date = {2022-05-28},

urldate = {2022-05-28},

journal = {Scientific Reports},

volume = {12},

number = {8964},

pages = {1 -- 8},

keywords = {entanglement, optical cavity, quantum frequency comb},

pubstate = {published},

tppubtype = {article}

}

@article{Fumiyoshi2022,

title = {Parent Hamiltonian as a benchmark problem for variational quantum eigensolvers},

author = {Fumiyoshi Kobayashi and Kosuke Mitarai and Keisuke Fujii},

url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.105.052415},

doi = {https://doi.org/10.1103/PhysRevA.105.052415},

year  = {2022},

date = {2022-05-10},

journal = {Phys. Rev. A},

volume = {105},

number = {052415},

issue = {5},

abstract = {The variational quantum eigensolver (VQE), which has attracted attention as a promising application of noisy intermediate-scale quantum devices, finds a ground state of a given Hamiltonian by variationally optimizing the parameters of quantum circuits called Ansätze. Since the difficulty of the optimization depends on the complexity of the problem Hamiltonian and the structure of the Ansätze, it has been difficult to systematically analyze the performance of optimizers for the VQE. To resolve this problem, we propose a technique to construct a benchmark problem whose ground state is guaranteed to be achievable with a given Ansatz by using the idea of a parent Hamiltonian of a low-depth parametrized quantum circuit. We compare the convergence of several optimizers by varying the distance of the initial parameters from the solution and find that the converged energies showed a threshold-like behavior depending on the distance. This work provides a systematic way to analyze optimizers for the VQE and contribute to the design of the Ansatz and its initial parameters.},

key = {Quantum algorithms},

keywords = {Quantum algorithms, Quantum benchmarking},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta2022,

title = {Optical Frequency Tweezers},

author = {Rikizo Ikuta and Masayo Yokota and Toshiki Kobayashi and Nobuyuki Imoto and Takashi Yamamoto},

url = {https://link.aps.org/doi/10.1103/PhysRevApplied.17.034012},

doi = {10.1103/PhysRevApplied.17.034012},

year  = {2022},

date = {2022-03-04},

urldate = {2022-03-04},

journal = {Physical Review Applied},

volume = {17},

pages = {034012},

abstract = {We show a concept of optical frequency tweezers for tweezing light in the optical frequency domain with a high resolution, which is the frequency version of optical tweezers for the spatial manipulation of microscopic objects. We report a proof-of-principle experiment via frequency conversion inside a cavity only for the converted light. Owing to the atypical configuration, the experiment successfully achieves the tweezing operation in the frequency domain, which picks light at a target frequency from the frequency-multiplexed input light and converts it to a different frequency, without touching any other light sitting in different frequency positions and shaking the frequency by the pump light.},

keywords = {quantum frequency comb, quantum internet},

pubstate = {published},

tppubtype = {article}

}

@article{Fujimoto2021,

title = {Entangled photon pair detection by superconducting nanowire single-photon detectors with a single-flux-quantum coincidence circuit},

author = {Rintaro Fujimoto and Shoichi Murakami and Toshiki Kobayashi and Rikizo Ikuta and Shigehito Miki and Shigeyuki Miyajima and Masahiro Yabuno and Fumihiro China and Hirotaka Terai and Nobuyuki Imoto and Takashi Yamamoto},

url = {https://iopscience.iop.org/article/10.35848/1882-0786/ac211e/meta},

doi = {https://doi.org/10.35848/1882-0786/ac211e},

year  = {2021},

date = {2021-09-07},

urldate = {2021-09-07},

journal = {Appl. Phys. Express},

volume = {14},

number = {10},

pages = {102001},

abstract = {We demonstrated the coincidence measurement of quantum light by superconducting nanowire single-photon detectors with a single-flux-quantum (SFQ) circuit as a signal processing circuit. By the quantum state tomography of a polarization-entangled photon pair, we evaluated the detection system based on the SFQ coincidence circuit. The estimated fidelity was almost the same value as that measured by using a detection system based on a conventional time-to-digital converter.},

keywords = {entanglement, superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta2021,

title = {Cavity-enhanced broadband photonic Rabi oscillation},

author = {Rikizo Ikuta and Toshiki Kobayashi and Tomohiro Yamazaki and Nobuyuki Imoto and Takashi Yamamoto},

url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.103.033709},

doi = {https://doi.org/10.1103/PhysRevA.103.033709},

year  = {2021},

date = {2021-03-18},

journal = {Physical Review A},

volume = {103},

pages = {033709},

abstract = {A coherent coupling among different energy photons provided by nonlinear optical interaction is regarded as a photonic version of the Rabi oscillation. Cavity enhancement of the nonlinearity reduces an energy requirement significantly and pushes the scalability of the frequency-encoded photonic circuit based on the photonic Rabi oscillation. However, the confinement of the photons in the cavity severely limits the number of interactable frequency modes. Here we demonstrate a wide-bandwidth and efficient photonic Rabi oscillation achieving full-cycle oscillation based on a cavity-enhanced nonlinear optical interaction with a monolithic integration. We also show its versatile manipulation beyond the frequency degree of freedom such as an all-optical control for polarizing photons with geometric phase. Our results will open up full control accessible to synthetic dimensional photonic systems over wide frequency modes as well as a large-scale photonic quantum information processing.},

keywords = {optical cavity, quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{Miyanishi2020,

title = {Robust entanglement distribution via telecom fibre assisted by an asynchronous counter-propagating laser light},

author = {Koichiro Miyanishi and Yoshiaki Tsujimoto and Rikizo Ikuta and Shigehito Miki and Masahiro Yabuno and Taro Yamashita and Hirotaka Terai and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto },

doi = {10.1038/s41534-020-0273-5},

year  = {2020},

date = {2020-05-20},

journal = {npj Quantum Information},

volume = {6},

number = {44},

abstract = {Distributing entangled photon pairs over noisy channels is an important task for various quantum information protocols. Encoding an entangled state in a decoherence-free subspace (DFS) formed by multiple photons is a promising way to circumvent the phase fluctuations and polarisation rotations in optical fibres. Recently, it has been shown that the use of a counter-propagating coherent light as an ancillary photon enables us to faithfully distribute entangled photon with success probability proportional to the transmittance of the optical fibres. Several proof-of-principle experiments have been demonstrated, in which entangled photon pairs from a sender side and the ancillary photon from a receiver side originate from the same laser source. In addition, bulk optics have been used to mimic the noises in optical fibres. Here, we demonstrate a DFS-based entanglement distribution over 1 km optical fibre using DFS formed by using fully independent light sources at the telecom band, and obtain a high-fidelity entangled state. This shows that the DFS-based scheme protects the entanglement against collective noise in 1 km optical fibre. In the experiment, we utilise an interference between asynchronous photons from continuous wave pumped spontaneous parametric down conversion (SPDC) and mode-locked coherent light pulse. After performing spectral and temporal filtering, the SPDC photons and light pulse are spectrally indistinguishable. This property allows us to observe high-visibility interference without performing active synchronisation between fully independent sources.},

keywords = {entanglement},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta2019,

title = {Frequency-Multiplexed Photon Pairs Over 1000 Modes from a Quadratic Nonlinear Optical Waveguide Resonator with a Singly Resonant Configuration},

author = {Rikizo Ikuta and Ryoya Tani and Masahiro Ishizaki and Shigehito Miki and Masahiro Yabuno and Hirotaka Terai and Nobuyuki Imoto and Takashi Yamamoto },

url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.193603},

doi = {10.1103/PhysRevLett.123.193603},

year  = {2019},

date = {2019-11-08},

urldate = {2019-11-08},

journal = {Phys. Rev. Lett.},

volume = {123},

pages = {193603},

organization = {arXiv},

abstract = {We demonstrate a frequency multiplexed photon pair generation based on a quadratic nonlinear optical waveguide inside a cavity which confines only signal photons without confining idler photons and the pump light. We monolithically constructed the photon pair generator by a periodically poled lithium niobate (PPLN) waveguide with a high reflective coating for the signal photons around 1600 nm and with antireflective coatings for the idler photons around 1520 nm and the pump light at 780 nm at the end faces of the PPLN waveguide. We observed a comblike photon pair generation with a mode spacing of the free spectral range of the cavity. Unlike the conventional multiple resonant photon pair generation experiments, the photon pair generation was incessant within a range of 80 nm without missing teeth due to a mismatch of the energy conservation and the cavity resonance condition of the photons, resulting in over 1000-mode frequency multiplexed photon pairs in this range.},

keywords = {optical cavity, quantum frequency comb, quantum internet},

pubstate = {published},

tppubtype = {article}

}

@article{Miki2019,

title = {Timing jitter characterization of the SFQ coincidence circuit by optically time-controlled signals from SSPDs},

author = {Shigehito Miki and Shigeyuki Miyajima and Masahiro Yabuno and Taro Yamashita and Takashi Yamamoto and Nobuyuki Imoto and Rikizo Ikuta and Robert Andrew Kirkwood and Robert Hadfield and Hirotaka Terai},

url = {https://ieeexplore.ieee.org/document/8675336},

doi = { 10.1109/TASC.2019.2906258},

issn = {1051-8223 },

year  = {2019},

date = {2019-03-27},

journal = {IEEE Transactions on Applied Superconductivity },

volume = {29},

number = {1302104 },

keywords = {superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{Yamamoto2019,

title = {Quantum Information Processing with Superconducting Nanowire Single-Photon Detectors},

author = {Takashi Yamamoto},

url = {http://search.ieice.org/bin/summary.php?id=e102-c_3_224&category=C&year=2019&lang=E&abst=},

doi = {10.1587/transele.2018SDI0002},

issn = {1745-1353},

year  = {2019},

date = {2019-03-01},

journal = {IEICE TRANS. ELECTRON.},

volume = {E102–C},

number = {3},

pages = {pp.224-229},

keywords = {superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{Hasegawa2019,

title = {Experimental time-reversed adaptive Bell measurement towards all-photonic quantum repeaters},

author = {Yasushi Hasegawa and Rikizo Ikuta and Nobuyuki Matsuda and Kiyoshi Tamaki and Hoi-Kwong Lo and Takashi Yamamoto and Koji Azuma and Nobuyuki Imoto },

url = {https://www.nature.com/articles/s41467-018-08099-5},

doi = {10.1038/s41467-018-08099-5},

year  = {2019},

date = {2019-01-28},

journal = {Nature Communications },

volume = {10},

pages = {378},

keywords = {quantum repeater},

pubstate = {published},

tppubtype = {article}

}

@article{Mizutani2019,

title = {Quantum key distribution with setting-choice-independently correlated light sources},

author = {Akihiro Mizutani and Go Kato and Koji Azuma and Marcos Curty and Rikizo Ikuta and Takashi Yamamoto and Nobuyuki Imoto and Hoi-Kwong Lo and Kiyoshi Tamaki},

url = {https://www.nature.com/articles/s41534-018-0122-y},

doi = {10.1038/s41534-018-0122-y},

year  = {2019},

date = {2019-01-23},

journal = {npj Quantum Information},

volume = {5},

pages = {8},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{Miki2018,

title = {Superconducting coincidence photon detector with short timing jitter},

author = {Shigehito Miki and Shigeyuki Miyajima and Masahiro Yabuno and Taro Yamashita and Takashi Yamamoto and Nobuyuki Imoto and Rikizo Ikuta and Robert A. Kirkwood and Robert H. Hadfield and Hirotaka Terai},

url = {https://aip.scitation.org/doi/10.1063/1.5037254},

doi = {10.1063/1.5037254},

year  = {2018},

date = {2018-06-26},

urldate = {2018-06-26},

journal = {Appl. Phys. Lett.},

volume = {112},

pages = {262601},

keywords = {superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta2018b,

title = {Frequency comb generation in a quadratic nonlinear waveguide resonator},

author = {Rikizo Ikuta and Motoki Asano and Ryoya Tani and Takashi Yamamoto and Nobuyuki Imoto},

url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-12-15551},

doi = {10.1364/OE.26.015551},

year  = {2018},

date = {2018-06-06},

journal = {Optics Express},

volume = {26},

number = {12},

pages = {15551--15558},

keywords = {optical cavity},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta2018,

title = {Polarization insensitive frequency conversion for an atom-photon entanglement distribution via a telecom network},

author = {Rikizo Ikuta and Toshiki Kobayashi and Tetsuo Kawakami and Shigehito Miki and Masahiro Yabuno and Taro Yamashita and Hirotaka Terai and Masato Koashi and Tetsuya Mukai and Takashi Yamamoto and Nobuyuki Imoto},

url = {https://www.nature.com/articles/s41467-018-04338-x},

doi = {10.1038/s41467-018-04338-x},

year  = {2018},

date = {2018-05-21},

journal = {Nature Communications},

volume = {9},

pages = {1997},

keywords = {atom, quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{Walker2018,

title = {Long-Distance Single Photon Transmission from a Trapped Ion via Quantum Frequency Conversion},

author = {Thomas Walker and Koichiro Miyanishi and Rikizo Ikuta and Hiroki Takahashi and Samir Vartabi Kashanian and Yoshiaki Tsujimoto and Kazuhiro Hayasaka and Takashi Yamamoto and Nobuyuki Imoto and Matthias Keller},

url = {https://doi.org/10.1103/PhysRevLett.120.203601

https://doi.org/10.1103/PhysRevLett.120.203601},

doi = {10.1103/PhysRevLett.120.203601},

year  = {2018},

date = {2018-05-15},

journal = {Phys. Rev. Lett.},

volume = {120},

pages = {203601},

publisher = {American Physical Society},

keywords = {atom, quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{Asano2018,

title = {An opto-electro-mechanical system based on evanescently-coupled optical microbottle and electromechanical resonator},

author = {Motoki Asano and Ryuichi Ohta and Takashi Yamamoto and Hajime Okamoto and Hiroshi Yamaguchi},

url = {https://doi.org/10.1063/1.5022115},

doi = {10.1063/1.5022115},

year  = {2018},

date = {2018-05-15},

journal = {Appl. Phys. Lett. },

volume = {112},

pages = {201103},

keywords = {optical cavity, optomechanics},

pubstate = {published},

tppubtype = {article}

}

@article{Uriri2018,

title = {Active control of a plasmonic metamaterial for quantum state engineering},

author = {S. A. Uriri and T. Tashima and X. Zhang and M. Asano and M. Bechu and D. Ö. Güney and T. Yamamoto and Ş. K. Özdemir and M. Wegener and M. S. Tame},

url = {https://doi.org/10.1103/PhysRevA.97.053810},

doi = {10.1103/PhysRevA.97.053810},

year  = {2018},

date = {2018-05-08},

journal = {Phys. Rev. A},

volume = {97},

pages = {053810},

keywords = {metamaterial},

pubstate = {published},

tppubtype = {article}

}

@article{tsujimoto2018high,

title = {High-fidelity entanglement swapping and generation of three-qubit GHZ state using asynchronous telecom photon pair sources},

author = {Yoshiaki Tsujimoto and Motoki Tanaka and Nobuo Iwasaki and Rikizo Ikuta and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

doi = {10.1038/s41598-018-19738-8},

year  = {2018},

date = {2018-01-23},

journal = {Scientific reports},

volume = {8},

number = {1},

pages = {1446},

publisher = {Nature Publishing Group},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.97.012112,

title = {Quantum weak and modular values in enlarged Hilbert spaces},

author = {Le Bin Ho and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.97.012112},

doi = {10.1103/PhysRevA.97.012112},

year  = {2018},

date = {2018-01-01},

journal = {Phys. Rev. A},

volume = {97},

pages = {012112},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.96.062321,

title = {Verification of hypergraph states},

author = {Tomoyuki Morimae and Yuki Takeuchi and Masahito Hayashi},

url = {https://link.aps.org/doi/10.1103/PhysRevA.96.062321},

doi = {10.1103/PhysRevA.96.062321},

year  = {2017},

date = {2017-12-01},

journal = {Phys. Rev. A},

volume = {96},

pages = {062321},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2058-9565-3-1-014002,

title = {Security of quantum key distribution with iterative sifting},

author = {Kiyoshi Tamaki and Hoi-Kwong Lo and Akihiro Mizutani and Go Kato and Charles Ci Wen Lim and Koji Azuma and Marcos Curty},

url = {http://stacks.iop.org/2058-9565/3/i=1/a=014002},

year  = {2017},

date = {2017-10-01},

journal = {Quantum Science and Technology},

volume = {3},

number = {1},

pages = {014002},

abstract = {Several quantum key distribution (QKD) protocols employ iterative sifting. After each quantum transmission round, Alice and Bob disclose part of their setting information (including their basis choices) for the detected signals. This quantum phase then ends when the basis dependent termination conditions are met, i.e., the numbers of detected signals per basis exceed certain pre-agreed threshold values. Recently, however, Pfister et al (2016 New J. Phys. 18 053001) showed that the basis dependent termination condition makes QKD insecure, especially in the finite key regime, and they suggested to disclose all the setting information after finishing the quantum phase. However, this protocol has two main drawbacks: it requires that Alice possesses a large memory, and she also needs to have some a priori knowledge about the transmission rate of the quantum channel. Here we solve these two problems by introducing a basis-independent termination condition to the iterative sifting in the finite key regime. The use of this condition, in combination with Azuma’s inequality, provides a precise estimation on the amount of privacy amplification that needs to be applied, thus leading to the security of QKD protocols, including the loss-tolerant protocol (Tamaki et al 2014 Phys. Rev. A 90 052314), with iterative sifting. Our analysis indicates that to announce the basis information after each quantum transmission round does not compromise the key generation rate of the loss-tolerant protocol. Our result allows the implementation of wider classes of classical post-processing techniques in QKD with quantified security.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2058-9565-3-1-014003,

title = {Information-theoretic security proof of differential-phase-shift quantum key distribution protocol based on complementarity},

author = {Akihiro Mizutani and Toshihiko Sasaki and Go Kato and Yuki Takeuchi and Kiyoshi Tamaki},

url = {http://stacks.iop.org/2058-9565/3/i=1/a=014003},

year  = {2017},

date = {2017-10-01},

journal = {Quantum Science and Technology},

volume = {3},

number = {1},

pages = {014003},

abstract = {We prove the information-theoretic security of the differential-phase-shift (DPS) quantum key distribution (QKD) protocol in the asymptotic regime based on the complementarity approach (arXiv:0704.3661 (2007)). Our security proof provides a slightly better key generation rate compared to the one derived in the previous security proof in (arXiv:1208.1995 (2012)) that is based on the Shor–Preskill approach (Shor and Preskill 2000 Phys. Rev. Lett. 85 441). This improvement is obtained because the complementarity approach can employ more detailed information on Alice’s sending state in estimating the leaked information to an eavesdropper. Moreover, we remove the necessity of the numerical calculation that was needed in the previous analysis to estimate the leaked information. This leads to an advantage that our security proof enables us to evaluate the security of the DPS protocol with any block size. This paper highlights one of the fundamental differences between the Shor–Preskill and the complementarity approaches.},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{Kobayashi:17,

title = {Mach-Zehnder interferometer using frequency-domain beamsplitter},

author = {Toshiki Kobayashi and Daisuke Yamazaki and Kenichiro Matsuki and Rikizo Ikuta and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-25-10-12052},

doi = {10.1364/OE.25.012052},

year  = {2017},

date = {2017-05-01},

journal = {Opt. Express},

volume = {25},

number = {10},

pages = {12052--12060},

publisher = {OSA},

abstract = {We demonstrate a first-order interference between coherent light at 1580 nm and 795 nm by using a frequency-domain Mach-Zehnder interferometer (MZI). The MZI is implemented by two frequency-domain BSs based on a second-order nonlinear optical effect in a periodically-poled lithium niobate waveguide with a strong pump light. The observed visibility is over 0.99 at 50% conversion efficiencies of the BSs. Toward photonic quantum information processing, sufficiently small background photon rate is necessary. From measurement results with a superconducting single photon detector (SSPD), we discuss the feasibility of the frequency-domain MZI in a quantum regime. Our estimation shows that the single photon interference with the visibility above 0.9 is feasible with practical settings.},

keywords = {quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{Tsujimoto:17,

title = {High visibility Hong-Ou-Mandel interference via a time-resolved coincidence measurement},

author = {Yoshiaki Tsujimoto and Yukihiro Sugiura and Motoki Tanaka and Rikizo Ikuta and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masato Koashi and Masahide Sasaki and Nobuyuki Imoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-25-11-12069},

doi = {10.1364/OE.25.012069},

year  = {2017},

date = {2017-05-01},

journal = {Opt. Express},

volume = {25},

number = {11},

pages = {12069--12080},

publisher = {OSA},

abstract = {A high visibility Hong-Ou-Mandel (HOM) interference between two independently prepared photons plays an important role in various photonic quantum information processing. In a standard HOM experiment using photons generated by pulse-pumped spontaneous parametric down conversion (SPDC), larger detection time windows than the coherence time of photons have been employed for measuring the HOM visibility and/or drawing the HOM dip. If large amounts of stray photons continuously exist within the detection time windows, employing small detection time windows is favorable for reducing the effect of background noises. Especially, such a setup is helpful for the HOM experiment using continuous wave (cw)-pumped SPDC and the time-resolved coincidence measurement. Here we argue that the method for determining the HOM visibility used in the previous cw experiments tends to suffer from distortion arising from biased contribution of the background noises. We then present a new method with unbiased treatment of the cw backgrounds. By using this method, we experimentally demonstrate a high visibility HOM interference of two heralded telecom photons independently generated by SPDC with employing cw pump light. An observed HOM visibility is 0.87 ± 0.04, which is as high as those observed by using pulse-pumped SPDC photons.},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{ikuta2017experimental,

title = {Experimental demonstration of robust entanglement distribution over reciprocal noisy channels assisted by a counter-propagating classical reference light},

author = {Rikizo Ikuta and Shota Nozaki and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

doi = {10.1038/s41598-017-05008-6},

year  = {2017},

date = {2017-05-01},

journal = {Scientific Reports},

volume = {7},

number = {1},

pages = {4819},

publisher = {Nature Publishing Group},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.95.042301,

title = {Differential-phase-shift quantum-key-distribution protocol with a small number of random delays},

author = {Yuki Hatakeyama and Akihiro Mizutani and Go Kato and Nobuyuki Imoto and Kiyoshi Tamaki},

url = {https://link.aps.org/doi/10.1103/PhysRevA.95.042301},

doi = {10.1103/PhysRevA.95.042301},

year  = {2017},

date = {2017-04-01},

journal = {Phys. Rev. A},

volume = {95},

pages = {042301},

publisher = {American Physical Society},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.95.032135,

title = {Generalized modular-value-based scheme and its generalized modular value},

author = {Le Bin Ho and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.95.032135},

doi = {10.1103/PhysRevA.95.032135},

year  = {2017},

date = {2017-03-01},

journal = {Phys. Rev. A},

volume = {95},

pages = {032135},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-18-12-123002,

title = {When a negative weak value −1 plays the counterpart of a probability 1},

author = {Kazuhiro Yokota and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/18/i=12/a=123002},

year  = {2016},

date = {2016-12-01},

journal = {New Journal of Physics},

volume = {18},

number = {12},

pages = {123002},

abstract = {When the weak value of a projector is 1, a quantum system behaves as in that eigenstate with probability 1. By definition, however, the weak value may take an anomalous value lying outside the range of probability like −1. From the viewpoint of a physical effect, we show that such a negative weak value of −1 can be regarded as the counterpart of the ordinary value of 1. Using photons, we experimentally verify it as the symmetrical shift in polarization depending on the weak value given by pre-postselection of the path state. Unlike observation of a weak value as an ensemble average via weak measurements, the effect of a weak value is definitely confirmed in Hong–Ou–Mandel effect: the symmetrical shift corresponding to the weak value can be directly observed as the rotation angle of a half wave plate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Asano:16b,

title = {Visible light emission from a silica microbottle resonator by second- and third-harmonic generation},

author = {Motoki Asano and Shoichi Komori and Rikizo Ikuta and Nobuyuki Imoto and {Ş}ahin K Özdemir and Takashi Yamamoto},

url = {http://ol.osa.org/abstract.cfm?URI=ol-41-24-5793},

doi = {10.1364/OL.41.005793},

year  = {2016},

date = {2016-12-01},

journal = {Opt. Lett.},

volume = {41},

number = {24},

pages = {5793--5796},

publisher = {OSA},

abstract = {We report the first observation of nonlinear harmonic generation and sum frequency generation (SFG) coupled with stimulated Raman scattering (SRS) via the second-order (χ(2)) and the third-order (χ(3)) nonlinearities in a silica microbottle resonator. The visible light emission due to third-harmonic generation (THG) was observed in both the output of a tapered fiber and the optical microscope images, which can be used to identify the axial mode profiles. SFG enabled by three- and four-wave mixing processes between the pump light and the light generated via SRS was also observed. Second-harmonic generation (SHG) and the SFG are enabled by χ(2) induced in silica by surface effects and multipole excitations.},

keywords = {optical cavity},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.94.062336,

title = {Ancilla-driven instantaneous quantum polynomial time circuit for quantum supremacy},

author = {Yuki Takeuchi and Yasuhiro Takahashi},

url = {https://link.aps.org/doi/10.1103/PhysRevA.94.062336},

doi = {10.1103/PhysRevA.94.062336},

year  = {2016},

date = {2016-12-01},

journal = {Phys. Rev. A},

volume = {94},

pages = {062336},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta:16,

title = {Heralded single excitation of atomic ensemble via solid-state-based telecom photon detection},

author = {Rikizo Ikuta and Toshiki Kobayashi and Kenichiro Matsuki and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Takashi Yamamoto and Masato Koashi and Tetsuya Mukai and Nobuyuki Imoto},

url = {http://www.osapublishing.org/optica/abstract.cfm?URI=optica-3-11-1279},

doi = {10.1364/OPTICA.3.001279},

year  = {2016},

date = {2016-11-01},

journal = {Optica},

volume = {3},

number = {11},

pages = {1279--1284},

publisher = {OSA},

abstract = {Telecom photonic quantum networks with matter quantum systems enable a rich variety of applications, such as long-distance quantum cryptography and one-way quantum computing. Preparation of a heralded single excitation (HSE) in an atomic ensemble by detecting a telecom wavelength photon having a correlation with the atomic excitation is an important step. Such a system has been demonstrated with a quantum frequency conversion (QFC) to telecom wavelength employing a Rb atomic cloud. However, the limited wavelength selection prevents the next step toward linking various kinds of matter quantum systems through long-distance fiber-based quantum communications. Here we for the first time, demonstrate HSE with a solid-state-based QFC and a detector for a telecom wavelength that will have the great advantage of the utility of mature telecom technologies. We unambiguously show that the demonstrated HSE indicates non-classical statistics by the direct measurement of the autocorrelation function.},

note = {press release by Osaka univ.},

keywords = {atom, quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{asano2016anomalous,

title = {Anomalous time delays and quantum weak measurements in optical microresonators},

author = {Motoki Asano and Konstantin Y Bliokh and Yury P Bliokh and Abraham G Kofman and Rikizo Ikuta and Takashi Yamamoto and Yuri S Kivshar and Lan Yang and Nobuyuki Imoto and {Ş}ahin K Özdemir and Franco Nori},

doi = {10.1038/ncomms13488},

year  = {2016},

date = {2016-11-01},

journal = {Nature communications},

volume = {7},

pages = {13488},

publisher = {Nature Publishing Group},

keywords = {optical cavity},

pubstate = {published},

tppubtype = {article}

}

@article{azuma2016fundamental,

title = {Fundamental rate-loss trade-off for the quantum internet},

author = {Koji Azuma and Akihiro Mizutani and Hoi-Kwong Lo},

doi = {10.1038/ncomms13523},

year  = {2016},

date = {2016-11-01},

journal = {Nature communications},

volume = {7},

pages = {13523},

publisher = {Nature Publishing Group},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.117.173601,

title = {Superradiant Phase Transition in a Superconducting Circuit in Thermal Equilibrium},

author = {Motoaki Bamba and Kunihiro Inomata and Yasunobu Nakamura},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.117.173601},

doi = {10.1103/PhysRevLett.117.173601},

year  = {2016},

date = {2016-10-01},

journal = {Phys. Rev. Lett.},

volume = {117},

pages = {173601},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yamashita2016superconducting,

title = {Superconducting nanowire single-photon detectors with non-periodic dielectric multilayers},

author = {Taro Yamashita and Kentaro Waki and Shigehito Miki and Robert A Kirkwood and Robert H Hadfield and Hirotaka Terai},

doi = {10.1038/srep35240},

year  = {2016},

date = {2016-10-01},

journal = {Scientific reports},

volume = {6},

pages = {35240},

publisher = {Nature Publishing Group},

keywords = {superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.94.033802,

title = {Maxwell boundary conditions imply non-Lindblad master equation},

author = {Motoaki Bamba and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.94.033802},

doi = {10.1103/PhysRevA.94.033802},

year  = {2016},

date = {2016-09-01},

journal = {Phys. Rev. A},

volume = {94},

pages = {033802},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1002/2016RS006073,

title = {Single‐ion spectroscopy system for the 2S1/2(F = 0) − 2D3/2(F = 2) transition in 171Yb+},

author = {Yasutaka Imai and Tatsuya Nishi and Masatoshi Nishizaki and Sho Kawajiri and Yuto Muroki and Rikizo Ikuta and Kai Matsumoto and Masao Kitano and Kazuhiko Sugiyama},

url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016RS006073},

doi = {10.1002/2016RS006073},

year  = {2016},

date = {2016-08-01},

journal = {Radio Science},

volume = {51},

number = {8},

pages = {1385-1395},

abstract = {Abstract We report on our system and scheme for single‐ion spectroscopy of the clock transition in 171Yb+. Spectroscopy of the clock transition requires decoupling of the state from the laser cooling cycle. We investigate this decoupling of the state by using independent light sources for driving of all the transitions between the hyperfine structures contained in the cooling and repumping transitions. We observe the carrier spectrum of the magnetic‐insensitive transition with a spectral width of 380 Hz.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1002/lpor.201500243,

title = {Observation of optomechanical coupling in a microbottle resonator},

author = {Motoki Asano and Yuki Takeuchi and Weijian Chen and {Ş}ahin K Özdemir and Rikizo Ikuta and Nobuyuki Imoto and Lan Yang and Takashi Yamamoto},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lpor.201500243},

doi = {10.1002/lpor.201500243},

year  = {2016},

date = {2016-07-01},

journal = {Laser & Photonics Reviews},

volume = {10},

number = {4},

pages = {603-611},

abstract = {Abstract In this work, we report optomechanical coupling, resolved sidebands and phonon lasing in a solid‐core microbottle resonator fabricated on a single mode optical fiber. Mechanical modes with quality factors (Qm) as high as 1.57 × 104 and 1.45 × 104 were observed, respectively, at the mechanical frequencies and . The maximum  Hz is close to the theoretical lower bound of 6 × 1012 Hz needed to overcome thermal decoherence for resolved‐sideband cooling of mechanical motion at room temperature, suggesting microbottle resonators as a possible platform for this endeavor. In addition to optomechanical effects, scatter‐induced mode splitting and ringing phenomena, which are typical for high‐quality optical resonances, were also observed in a microbottle resonator.},

keywords = {optical cavity, optomechanics},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.93.052307,

title = {Blind quantum computation over a collective-noise channel},

author = {Yuki Takeuchi and Keisuke Fujii and Rikizo Ikuta and Takashi Yamamoto and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.93.052307},

doi = {10.1103/PhysRevA.93.052307},

year  = {2016},

date = {2016-05-01},

journal = {Phys. Rev. A},

volume = {93},

pages = {052307},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Asano:16,

title = {Stimulated Brillouin scattering and Brillouin-coupled four-wave-mixing in a silica microbottle resonator},

author = {Motoki Asano and Yuki Takeuchi and {Ş}ahin K Özdemir and Rikizo Ikuta and Lan Yang and Nobuyuki Imoto and Takashi Yamamoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-24-11-12082},

doi = {10.1364/OE.24.012082},

year  = {2016},

date = {2016-05-01},

journal = {Opt. Express},

volume = {24},

number = {11},

pages = {12082--12092},

publisher = {OSA},

abstract = {We report the first observation of stimulated Brillouin scattering (SBS) with Brillouin lasing, and Brillouin-coupled four-wave-mixing (FWM) in an ultra-high-Q silica microbottle resonator. The Brillouin lasing was observed at the frequency of ΩB $=$ 2π × 10.4 GHz with a threshold power of 0.45 mW. Coupling between Brillouin and FWM was observed in both backward and forward scattering directions with separations of 2ΩB. At a pump power of 10 mW, FWM spacing reached to 7th and 9th order anti-Stokes and Stokes, respectively.},

keywords = {optical cavity, optomechanics},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.93.042325,

title = {Security of quantum key distribution with light sources that are not independently and identically distributed},

author = {Yuichi Nagamatsu and Akihiro Mizutani and Rikizo Ikuta and Takashi Yamamoto and Nobuyuki Imoto and Kiyoshi Tamaki},

url = {https://link.aps.org/doi/10.1103/PhysRevA.93.042325},

doi = {10.1103/PhysRevA.93.042325},

year  = {2016},

date = {2016-04-01},

journal = {Phys. Rev. A},

volume = {93},

pages = {042325},

publisher = {American Physical Society},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{kobayashi2016frequency,

title = {Frequency-domain Hong-Ou-Mandel interference},

author = {Toshiki Kobayashi and Rikizo Ikuta and Shuto Yasui and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://qi.mp.es.osaka-u.ac.jp/imotolab/index-j/activity/NP-2016/index.html

https://www.nature.com/articles/nphoton.2016.74},

doi = {10.1038/nphoton.2016.74},

year  = {2016},

date = {2016-04-01},

journal = {Nature Photonics},

volume = {10},

number = {7},

pages = {441},

publisher = {Nature Publishing Group},

note = {press release by Osaka univ. (see "Links")},

keywords = {press, quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1063/1.4948922,

title = {Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity},

author = {Motoki Asano and {Ş}ahin K Özdemir and Weijian Chen and Rikizo Ikuta and Lan Yang and Nobuyuki Imoto and Takashi Yamamoto},

url = {https://doi.org/10.1063/1.4948922},

doi = {10.1063/1.4948922},

year  = {2016},

date = {2016-01-01},

journal = {Applied Physics Letters},

volume = {108},

number = {18},

pages = {181105},

keywords = {optical cavity},

pubstate = {published},

tppubtype = {article}

}

@article{HO20162129,

title = {Full characterization of modular values for finite-dimensional systems},

author = {Le Bin Ho and Nobuyuki Imoto},

url = {http://www.sciencedirect.com/science/article/pii/S0375960116301773},

doi = {https://doi.org/10.1016/j.physleta.2016.05.005},

issn = {0375-9601},

year  = {2016},

date = {2016-01-01},

journal = {Physics Letters A},

volume = {380},

number = {25},

pages = {2129 - 2135},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{asano2015distillation,

title = {Distillation of photon entanglement using a plasmonic metamaterial},

author = {Motoki Asano and Muriel Bechu and Mark Tame and {Ş}ahin K Özdemir and Rikizo Ikuta and Durdu Ö Güney and Takashi Yamamoto and Lan Yang and Martin Wegener and Nobuyuki Imoto},

doi = {10.1038/srep18313},

year  = {2015},

date = {2015-12-01},

journal = {Scientific reports},

volume = {5},

pages = {18313},

publisher = {Nature Publishing Group},

keywords = {entanglement, metamaterial},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.92.060303,

title = {Robustness of the round-robin differential-phase-shift quantum-key-distribution protocol against source flaws},

author = {Akihiro Mizutani and Nobuyuki Imoto and Kiyoshi Tamaki},

url = {https://link.aps.org/doi/10.1103/PhysRevA.92.060303},

doi = {10.1103/PhysRevA.92.060303},

year  = {2015},

date = {2015-12-01},

journal = {Phys. Rev. A},

volume = {92},

pages = {060303},

publisher = {American Physical Society},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{Asano:15,

title = {Analytical investigation of optical vortices emitted from a collectively polarized dipole array},

author = {Motoki Asano and Tohru Takahashi},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-23-21-27998},

doi = {10.1364/OE.23.027998},

year  = {2015},

date = {2015-10-01},

journal = {Opt. Express},

volume = {23},

number = {21},

pages = {27998--28011},

publisher = {OSA},

abstract = {Many approaches for producing optical vortices have been developed both for fundamental interests of science and for engineering applications. In particular, the approach with direct excitation of several emitters has a potential to control the topological charges with a control of the source conditions without any modifications of structures of the system. In this paper, we investigate the propagation properties of the optical vortices emitted from a collectively polarized electric dipole array as a simple model of the several emitters. Using an analytical approach based on the Jacobi-Anger expansion, we derive a relationship between the topological charge of the optical vortices and the source conditions of the emitter, and clarify and report our new finding; there exists an intrinsic split of the singular points in the electric field due to the spin-orbit interaction of the dipole fields.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-17-9-093011,

title = {Finite-key security analysis of quantum key distribution with imperfect light sources},

author = {Akihiro Mizutani and Marcos Curty and Charles Ci Wen Lim and Nobuyuki Imoto and Kiyoshi Tamaki},

url = {http://stacks.iop.org/1367-2630/17/i=9/a=093011},

year  = {2015},

date = {2015-09-01},

journal = {New Journal of Physics},

volume = {17},

number = {9},

pages = {093011},

abstract = {In recent years, the gap between theory and practice in quantum key distribution (QKD) has been significantly narrowed, particularly for QKD systems with arbitrarily flawed optical receivers. The status for QKD systems with imperfect light sources is however less satisfactory, in the sense that the resulting secure key rates are often overly dependent on the quality of state preparation. This is especially the case when the channel loss is high. Very recently, to overcome this limitation, Tamaki et al proposed a QKD protocol based on the so-called ‘rejected data analysis’, and showed that its security—in the limit of infinitely long keys—is almost independent of any encoding flaw in the qubit space, being this protocol compatible with the decoy state method. Here, as a step towards practical QKD, we show that a similar conclusion is reached in the finite-key regime, even when the intensity of the light source is unstable. More concretely, we derive security bounds for a wide class of realistic light sources and show that the bounds are also efficient in the presence of high channel loss. Our results strongly suggest the feasibility of long distance provably secure communication with imperfect light sources.},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevB.92.075312,

title = {Quantum state tomography of large nuclear spins in a semiconductor quantum well: Optimal robustness against errors as quantified by condition numbers},

author = {Adam Miranowicz and {Ş}ahin K Özdemir and Jiří Bajer and Go Yusa and Nobuyuki Imoto and Yoshiro Hirayama and Franco Nori},

url = {https://link.aps.org/doi/10.1103/PhysRevB.92.075312},

doi = {10.1103/PhysRevB.92.075312},

year  = {2015},

date = {2015-08-01},

journal = {Phys. Rev. B},

volume = {92},

pages = {075312},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{6998043,

title = {Fabrication and Characterization of Superconducting Nanowire Single-Photon Detectors on Si Waveguide},

author = {Kentaro Waki and Taro Yamashita and Shin-ichiro Inoue and Shigehito Miki and Hirotaka Terai and Rikizo Ikuta and Takashi Yamamoto and Nobuyuki Imoto},

doi = {10.1109/TASC.2014.2385836},

issn = {1051-8223},

year  = {2015},

date = {2015-06-01},

journal = {IEEE Transactions on Applied Superconductivity},

volume = {25},

number = {3},

pages = {1-4},

keywords = {superconducting detector},

pubstate = {published},

tppubtype = {article}

}

@article{Tsujimoto:15,

title = {Extracting an entangled photon pair from collectively decohered pairs at a telecommunication wavelength},

author = {Yoshiaki Tsujimoto and Yukihiro Sugiura and Makoto Ando and Daisuke Katsuse and Rikizo Ikuta and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-23-10-13545},

doi = {10.1364/OE.23.013545},

year  = {2015},

date = {2015-05-01},

journal = {Opt. Express},

volume = {23},

number = {10},

pages = {13545--13553},

publisher = {OSA},

abstract = {We experimentally demonstrated entanglement extraction scheme by using photons at the telecommunication band for optical-fiber-based quantum communications. We generated two pairs of non-degenerate polarization entangled photons at 780 nm and 1551 nm by spontaneous parametric down-conversion and distributed the two photons at 1551 nm through a collective phase damping channel which gives the same amount of random phase shift on the two photons. Through local operation and classical communication, we extracted an entangled photon pair from two phase-disturbed photon pairs. An observed fidelity of the extracted photon pair to a maximally entangled photon pair was 0.73 textpm 0.07 which clearly shows the recovery of entanglement.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevX.4.041039,

title = {Measurement-Free Topological Protection Using Dissipative Feedback},

author = {Keisuke Fujii and Makoto Negoro and Nobuyuki Imoto and Masahiro Kitagawa},

url = {https://link.aps.org/doi/10.1103/PhysRevX.4.041039},

doi = {10.1103/PhysRevX.4.041039},

year  = {2014},

date = {2014-12-01},

journal = {Phys. Rev. X},

volume = {4},

pages = {041039},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.90.062123,

title = {Optimal two-qubit tomography based on local and global measurements: Maximal robustness against errors as described by condition numbers},

author = {Adam Miranowicz and Karol Bartkiewicz and Jan Peřina and Masato Koashi and Nobuyuki Imoto and Franco Nori},

url = {https://link.aps.org/doi/10.1103/PhysRevA.90.062123},

doi = {10.1103/PhysRevA.90.062123},

year  = {2014},

date = {2014-12-01},

journal = {Phys. Rev. A},

volume = {90},

pages = {062123},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.90.022304,

title = {Quantum algorithm for an additive approximation of Ising partition functions},

author = {Akira Matsuo and Keisuke Fujii and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.90.022304},

doi = {10.1103/PhysRevA.90.022304},

year  = {2014},

date = {2014-08-01},

journal = {Phys. Rev. A},

volume = {90},

pages = {022304},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-16-7-073003,

title = {A weak-value model for virtual particles supplying the electric current in graphene: the minimal conductivity and the Schwinger mechanism},

author = {Kazuhiro Yokota and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/16/i=7/a=073003},

year  = {2014},

date = {2014-07-01},

journal = {New Journal of Physics},

volume = {16},

number = {7},

pages = {073003},

abstract = {We propose a model for the electric current in graphene in which electric carriers are supplied by virtual particles allowed by the uncertainty relations. The process to make a virtual particle real is described by a weak value of a group velocity: the velocity is requisite for the electric field to give the virtual particle the appropriate changes of both energy and momentum. With the weak value, we approximately estimate the electric current, considering the ballistic transport of the electric carriers. The current shows the quasi-Ohmic with the minimal conductivity of the order of ##IMG## [http://ej.iop.org/images/1367-2630/16/7/073003/njp496797ieqn1.gif] $e^2/h$ per channel. Crossing a certain ballistic time scale, it is brought to obey the Schwinger mechanism.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mizutani2014measurement,

title = {Measurement-device-independent quantum key distribution for Scarani-Acin-Ribordy-Gisin 04 protocol},

author = {Akihiro Mizutani and Kiyoshi Tamaki and Rikizo Ikuta and Takashi Yamamoto and Nobuyuki Imoto},

doi = {10.1038/srep05236},

year  = {2014},

date = {2014-06-01},

journal = {Scientific reports},

volume = {4},

pages = {5236},

publisher = {Nature Publishing Group},

keywords = {quantum cryptography},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta:14,

title = {Frequency down-conversion of 637 nm light to the telecommunication band for non-classical light emitted from NV centers in diamond},

author = {Rikizo Ikuta and Toshiki Kobayashi and Shuto Yasui and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masato Koashi and Masahide Sasaki and Zhen Wang and Nobuyuki Imoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-22-9-11205},

doi = {10.1364/OE.22.011205},

year  = {2014},

date = {2014-05-01},

journal = {Opt. Express},

volume = {22},

number = {9},

pages = {11205--11214},

publisher = {OSA},

abstract = {We demonstrate a low-noise frequency down-conversion of photons at 637 nm to the telecommunication band at 1587 nm by the difference frequency generation in a periodically-poled lithium niobate. An internal conversion efficiency of the converter is estimated to be 0.44 at the maximum which is achieved by a pump power of 0.43 W, whereas a rate of internal background photons caused by the strong cw pump laser is estimated to be 9 kHz/mW within a bandwidth of about 1 nm. By using the experimental values related to the intrinsic property of the converter, and using the intensity correlation and the average photon number of a 637 nm input light pulse, we derive the intensity correlation of a converted telecom light pulse. Then we discuss feasibility of a single-photon frequency conversion to the telecommunication band for a long-distance quantum communication based on NV centers in diamond.},

keywords = {quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-16-2-023005,

title = {Universal gates for transforming multipartite entangled Dicke states},

author = {Toshiki Kobayashi and Rikizo Ikuta and {Ş}ahin K Özdemir and Mark Tame and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/16/i=2/a=023005},

year  = {2014},

date = {2014-02-01},

journal = {New Journal of Physics},

volume = {16},

number = {2},

pages = {023005},

abstract = {We determine the minimal number of qubits that it is necessary to have access to in order to transform Dicke states into other Dicke states. In general, the number of qubits in Dicke states cannot be increased via transformation gates by accessing only a single qubit, in direct contrast to other multipartite entangled states such as GHZ, W and cluster states. We construct a universal optimal gate which adds spin-up qubits or spin-down qubits to any Dicke state by minimal access. We also show the existence of a universal gate which transforms any size of Dicke state as long as it has access to at least the required number of qubits. Our results have important consequences for the generation of Dicke states in physical systems such as ion traps, all-optical setups and cavity-quantum electrodynamic settings where they can be used for a variety of quantum information processing tasks.},

keywords = {entanglement},

pubstate = {published},

tppubtype = {article}

}

@article{Ikuta:13,

title = {Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon level},

author = {Rikizo Ikuta and Toshiki Kobayashi and Hiroshi Kato and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masahide Sasaki and Zhen Wang and Masato Koashi and Nobuyuki Imoto},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-23-27865},

doi = {10.1364/OE.21.027865},

year  = {2013},

date = {2013-11-01},

journal = {Opt. Express},

volume = {21},

number = {23},

pages = {27865--27872},

publisher = {OSA},

abstract = {We experimentally demonstrate that both of the two output light pulses of different wavelengths from a wavelength converter with various branching ratios preserve phase information of an input light at a single-photon level. In our experiment, we converted temporally-separated two coherent light pulses with average photon numbers of $sim$ 0.1 at 780 nm to light pulses at 1522 nm by using difference-frequency generation in a periodically-poled lithium niobate waveguide. We observed an interference between temporally-separated two modes for both the converted and the unconverted light pulses at various values of the conversion efficiency. We observed interference visibilities greater than 0.88 without suppressing the background noises for any value of the conversion efficiency the wavelength converter achieves. At a conversion efficiency of $sim$ 0.5, the observed visibilities are 0.98 for the unconverted light and 0.99 for the converted light. Such a phase-preserving wavelength converter with high visibilities will be useful for manipulating quantum states encoded in the frequency degrees of freedom.},

keywords = {quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.88.042317,

title = {Nonclassical two-photon interference between independent telecommunication light pulses converted by difference-frequency generation},

author = {Rikizo Ikuta and Toshiki Kobayashi and Hiroshi Kato and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masato Koashi and Masahide Sasaki and Zhen Wang and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.88.042317},

doi = {10.1103/PhysRevA.88.042317},

year  = {2013},

date = {2013-10-01},

journal = {Phys. Rev. A},

volume = {88},

pages = {042317},

publisher = {American Physical Society},

keywords = {quantum frequency conversion},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.111.020502,

title = {Secure Entanglement Distillation for Double-Server Blind Quantum Computation},

author = {Tomoyuki Morimae and Keisuke Fujii},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.111.020502},

doi = {10.1103/PhysRevLett.111.020502},

year  = {2013},

date = {2013-07-01},

journal = {Phys. Rev. Lett.},

volume = {111},

pages = {020502},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.87.052325,

title = {Robustness of quantum communication based on a decoherence-free subspace using a counter-propagating weak coherent light pulse},

author = {Hidetoshi Kumagai and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.87.052325},

doi = {10.1103/PhysRevA.87.052325},

year  = {2013},

date = {2013-05-01},

journal = {Phys. Rev. A},

volume = {87},

pages = {052325},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.87.050301,

title = {Blind quantum computation protocol in which Alice only makes measurements},

author = {Tomoyuki Morimae and Keisuke Fujii},

url = {https://link.aps.org/doi/10.1103/PhysRevA.87.050301},

doi = {10.1103/PhysRevA.87.050301},

year  = {2013},

date = {2013-05-01},

journal = {Phys. Rev. A},

volume = {87},

pages = {050301},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.110.120502,

title = {Measurement-Based Quantum Computation on Symmetry Breaking Thermal States},

author = {Keisuke Fujii and Yoshifumi Nakata and Masayuki Ohzeki and Mio Murao},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.110.120502},

doi = {10.1103/PhysRevLett.110.120502},

year  = {2013},

date = {2013-03-01},

journal = {Phys. Rev. Lett.},

volume = {110},

pages = {120502},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.87.022321,

title = {Fundamental limit to qubit control with coherent field},

author = {Kazuhiro Igeta and Nobuyuki Imoto and Masato Koashi},

url = {https://link.aps.org/doi/10.1103/PhysRevA.87.022321},

doi = {10.1103/PhysRevA.87.022321},

year  = {2013},

date = {2013-02-01},

journal = {Phys. Rev. A},

volume = {87},

pages = {022321},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.87.010301,

title = {High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectors},

author = {Rikizo Ikuta and Hiroshi Kato and Yoshiaki Kusaka and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masato Koashi and Masahide Sasaki and Zhen Wang and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.87.010301},

doi = {10.1103/PhysRevA.87.010301},

year  = {2013},

date = {2013-01-01},

journal = {Phys. Rev. A},

volume = {87},

pages = {010301},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevE.86.051121,

title = {Duality analysis on random planar lattices},

author = {Masayuki Ohzeki and Keisuke Fujii},

url = {https://link.aps.org/doi/10.1103/PhysRevE.86.051121},

doi = {10.1103/PhysRevE.86.051121},

year  = {2012},

date = {2012-11-01},

journal = {Phys. Rev. E},

volume = {86},

pages = {051121},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{morimae2012blind,

title = {Blind topological measurement-based quantum computation},

author = {Tomoyuki Morimae and Keisuke Fujii},

doi = {10.1038/ncomms2043},

year  = {2012},

date = {2012-09-01},

journal = {Nature communications},

volume = {3},

pages = {1036},

publisher = {Nature Publishing Group},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-14-8-083021,

title = {A strange weak value in spontaneous pair productions via a supercritical step potential},

author = {Kazuhiro Yokota and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/14/i=8/a=083021},

year  = {2012},

date = {2012-08-01},

journal = {New Journal of Physics},

volume = {14},

number = {8},

pages = {083021},

abstract = {We consider a case when a weak value is introduced as a physical quantity rather than as an average of weak measurements. The case we treat is a time evolution of a particle by the 1 + 1-dimensional Dirac equation. In particular, in a spontaneous pair production via a supercritical step potential, a quantitative explanation can be given by a weak value for the group velocity of the particle. We also show that the condition for the pair production (supercriticality) corresponds to the condition when the weak value takes a strange value (superluminal velocity).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.86.020303,

title = {Error and loss tolerances of surface codes with general lattice structures},

author = {Keisuke Fujii and Yuuki Tokunaga},

url = {https://link.aps.org/doi/10.1103/PhysRevA.86.020303},

doi = {10.1103/PhysRevA.86.020303},

year  = {2012},

date = {2012-08-01},

journal = {Phys. Rev. A},

volume = {86},

pages = {020303},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{morimae2012not,

title = {Not all physical errors can be linear CPTP maps in a correlation space},

author = {Tomoyuki Morimae and Keisuke Fujii},

doi = {10.1038/srep00508},

year  = {2012},

date = {2012-07-01},

journal = {Scientific Reports},

volume = {2},

pages = {508},

publisher = {Nature Publishing Group},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.85.062309,

title = {Quantum repeaters and computation by a single module: Remote nondestructive parity measurement},

author = {Koji Azuma and Hitoshi Takeda and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.85.062309},

doi = {10.1103/PhysRevA.85.062309},

year  = {2012},

date = {2012-06-01},

journal = {Phys. Rev. A},

volume = {85},

pages = {062309},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.85.032338,

title = {Computational power and correlation in a quantum computational tensor network},

author = {Keisuke Fujii and Tomoyuki Morimae},

url = {https://link.aps.org/doi/10.1103/PhysRevA.85.032338},

doi = {10.1103/PhysRevA.85.032338},

year  = {2012},

date = {2012-03-01},

journal = {Phys. Rev. A},

volume = {85},

pages = {032338},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.85.010304,

title = {Topologically protected measurement-based quantum computation on the thermal state of a nearest-neighbor two-body Hamiltonian with spin-3/2 particles},

author = {Keisuke Fujii and Tomoyuki Morimae},

url = {https://link.aps.org/doi/10.1103/PhysRevA.85.010304},

doi = {10.1103/PhysRevA.85.010304},

year  = {2012},

date = {2012-01-01},

journal = {Phys. Rev. A},

volume = {85},

pages = {010304},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ikuta2011wide,

title = {Wide-band quantum interface for visible-to-telecommunication wavelength conversion},

author = {Rikizo Ikuta and Yoshiaki Kusaka and Tsuyoshi Kitano and Hiroshi Kato and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://dx.doi.org/10.1038/ncomms1544},

doi = {10.1038/ncomms1544},

year  = {2011},

date = {2011-11-01},

journal = {Nature Communications},

volume = {2},

pages = {537},

publisher = {Nature Publishing Group},

note = {press release by Osaka univ.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-13-10-103003,

title = {An optical fusion gate for W-states},

author = {{Ş}ahin K Özdemir and Eiji Matsunaga and Toshiyuki Tashima and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/13/i=10/a=103003},

year  = {2011},

date = {2011-10-01},

journal = {New Journal of Physics},

volume = {13},

number = {10},

pages = {103003},

abstract = {We introduce a simple optical gate to fuse arbitrary-size polarization entangled W-states to prepare larger W-states. The gate requires a polarizing beam splitter (PBS), a half-wave plate (HWP) and two photon detectors. We study, numerically and analytically, the necessary resource consumption for preparing larger W-states by fusing smaller ones with the proposed fusion gate. We show analytically that resource requirement scales at most sub-exponentially with the increasing size of the state to be prepared. We numerically determine the resource cost for fusion without recycling where W-states of arbitrary size can be optimally prepared. Moreover, we introduce another strategy that is based on recycling and outperforms the optimal strategy for the non-recycling case.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.84.022308,

title = {Cheat-sensitive commitment of a classical bit coded in a block of $m$ times $n$ round-trip qubits},

author = {Kaoru Shimizu and Hiroyuki Fukasaka and Kiyoshi Tamaki and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.84.022308},

doi = {10.1103/PhysRevA.84.022308},

year  = {2011},

date = {2011-08-01},

journal = {Phys. Rev. A},

volume = {84},

pages = {022308},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.106.110503,

title = {Efficient Decoherence-Free Entanglement Distribution over Lossy Quantum Channels},

author = {Rikizo Ikuta and Yohei Ono and Toshiyuki Tashima and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.106.110503},

doi = {10.1103/PhysRevLett.106.110503},

year  = {2011},

date = {2011-03-01},

journal = {Phys. Rev. Lett.},

volume = {106},

pages = {110503},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.83.012314,

title = {Optimal local expansion of $W$ states using linear optics and Fock states},

author = {Rikizo Ikuta and Toshiyuki Tashima and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.83.012314},

doi = {10.1103/PhysRevA.83.012314},

year  = {2011},

date = {2011-01-01},

journal = {Phys. Rev. A},

volume = {83},

pages = {012314},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.105.210503,

title = {Demonstration of Local Expansion Toward Large-Scale Entangled Webs},

author = {Toshiyuki Tashima and Tsuyoshi Kitano and {Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.105.210503},

doi = {10.1103/PhysRevLett.105.210503},

year  = {2010},

date = {2010-11-01},

journal = {Phys. Rev. Lett.},

volume = {105},

pages = {210503},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.81.022325,

title = {Tight bound on coherent-state-based entanglement generation over lossy channels},

author = {Koji Azuma and Naoya Sota and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.81.022325},

doi = {10.1103/PhysRevA.81.022325},

year  = {2010},

date = {2010-02-01},

journal = {Phys. Rev. A},

volume = {81},

pages = {022325},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{SEKI20101534,

title = {Comparison of timing jitter between NbN superconducting single-photon detector and avalanche photodiode},

author = {Tadakiyo Seki and Hiroyuki Shibata and Hiroki Takesue and Yasuhiro Tokura and Nobuyuki Imoto},

url = {http://www.sciencedirect.com/science/article/pii/S0921453410004120},

doi = {https://doi.org/10.1016/j.physc.2010.05.156},

issn = {0921-4534},

year  = {2010},

date = {2010-01-01},

journal = {Physica C: Superconductivity and its Applications},

volume = {470},

number = {20},

pages = {1534 - 1537},

note = {Proceedings of the 22nd International Symposium on Superconductivity (ISS 2009)},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.80.060303,

title = {Optimal entanglement generation for efficient hybrid quantum repeaters},

author = {Koji Azuma and Naoya Sota and Ryo Namiki and {Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.80.060303},

doi = {10.1103/PhysRevA.80.060303},

year  = {2009},

date = {2009-12-01},

journal = {Phys. Rev. A},

volume = {80},

pages = {060303},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-11-11-113033,

title = {Boosting up quantum key distribution by learning statistics of practical single-photon sources},

author = {Yoritoshi Adachi and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/11/i=11/a=113033},

year  = {2009},

date = {2009-11-01},

journal = {New Journal of Physics},

volume = {11},

number = {11},

pages = {113033},

abstract = {We propose a simple quantum-key-distribution (QKD) scheme for practical single-photon sources (SPSs), which works even with a moderate suppression of the second-order correlation g (2) of the source. The scheme utilizes a passive preparation of a decoy state by monitoring a fraction of the signal via an additional beam splitter and a detector at the sender's side to monitor photon-number splitting attacks. We show that the achievable distance increases with the precision with which the sub-Poissonian tendency is confirmed in higher photon-number distribution of the source, rather than with actual suppression of the multiphoton emission events. We present an example of the secure key generation rate in the case of a poor SPS with g (2) =0.19, in which no secure key is produced with the conventional QKD scheme, and show that learning the photon-number distribution up to several numbers is sufficient for achieving almost the same distance as that of an ideal SPS.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.80.032302,

title = {Unconditional security of the Bennett 1992 quantum-key-distribution scheme with a strong reference pulse},

author = {Kiyoshi Tamaki and Norbert Lütkenhaus and Masato Koashi and Jamie Batuwantudawe},

url = {https://link.aps.org/doi/10.1103/PhysRevA.80.032302},

doi = {10.1103/PhysRevA.80.032302},

year  = {2009},

date = {2009-09-01},

journal = {Phys. Rev. A},

volume = {80},

pages = {032302},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.80.032306,

title = {Optimal mirror phase-covariant cloning},

author = {Karol Bartkiewicz and Adam Miranowicz and {Ş}ahin K Özdemir},

url = {https://link.aps.org/doi/10.1103/PhysRevA.80.032306},

doi = {10.1103/PhysRevA.80.032306},

year  = {2009},

date = {2009-09-01},

journal = {Phys. Rev. A},

volume = {80},

pages = {032306},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.102.130502,

title = {Local Transformation of Two Einstein-Podolsky-Rosen Photon Pairs into a Three-Photon $W$ State},

author = {Toshiyuki Tashima and Tetsuroh Wakatsuki and {Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.102.130502},

doi = {10.1103/PhysRevLett.102.130502},

year  = {2009},

date = {2009-04-01},

journal = {Phys. Rev. Lett.},

volume = {102},

pages = {130502},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-11-4-045018,

title = {Simple security proof of quantum key distribution based on complementarity},

author = {Masato Koashi},

url = {http://stacks.iop.org/1367-2630/11/i=4/a=045018},

year  = {2009},

date = {2009-04-01},

journal = {New Journal of Physics},

volume = {11},

number = {4},

pages = {045018},

abstract = {We present an approach to the unconditional security of quantum key distribution protocols based on a complementarity argument. The approach is applicable to, but not limited to, every case that has been treated via the argument by Shor and Preskill based on entanglement distillation, with a benefit of decoupling of the error correction from the privacy amplification. It can also treat cases with uncharacterized apparatuses. We derive a secure key rate for the Bennett–Brassard-1984 protocol with an arbitrary source characterized only by a single parameter representing the basis dependence.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-11-3-033011,

title = {Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair},

author = {Kazuhiro Yokota and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/11/i=3/a=033011},

year  = {2009},

date = {2009-03-01},

journal = {New Journal of Physics},

volume = {11},

number = {3},

pages = {033011},

abstract = {We implemented a joint weak measurement of the trajectories of two photons in a photonic version of Hardy's experiment. The joint weak measurement has been performed via an entangled meter state in polarization degrees of freedom of the two photons. Unlike Hardy's original argument in which the contradiction is inferred by retrodiction, our experiment reveals its paradoxical nature as preposterous values actually read out from the meter. Such a direct observation of a paradox gives us new insights into the spooky action of quantum mechanics.},

note = {IOP press release, New Journal of Physics - Best of 2009},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-11-2-023024,

title = {Local expansion of photonic W state using a polarization-dependent beamsplitter},

author = {Toshiyuki Tashima and {Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/11/i=2/a=023024},

year  = {2009},

date = {2009-02-01},

journal = {New Journal of Physics},

volume = {11},

number = {2},

pages = {023024},

abstract = {We propose a simple probabilistic optical gate to expand polarization entangled W states. The gate uses one polarization-dependent beamsplitter and a horizontally polarized single photon as an ancilla. The gate post-selectively expands N -photon W states to ( N +1)-photon W states. A feasibility analysis considering the realistic experimental conditions shows that the scheme is within the reach of the current quantum optical technologies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.79.020302,

title = {Compact Toffoli gate using weighted graph states},

author = {Mark S Tame and {Ş}ahin K Özdemir and Masato Koashi and Nobuyuki Imoto and Myungshik S Kim},

url = {https://link.aps.org/doi/10.1103/PhysRevA.79.020302},

doi = {10.1103/PhysRevA.79.020302},

year  = {2009},

date = {2009-02-01},

journal = {Phys. Rev. A},

volume = {79},

pages = {020302},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Xiao:08,

title = {Quantum nondemolition measurement of photon number via optical Kerr effect in an ultra-high-Q microtoroid cavity},

author = {Yun-Feng Xiao and {Ş}ahin K Özdemir and Venkat Gaddam and Chun-Hua Dong and Nobuyuki Imoto and Lan Yang},

url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-16-26-21462},

doi = {10.1364/OE.16.021462},

year  = {2008},

date = {2008-12-01},

journal = {Opt. Express},

volume = {16},

number = {26},

pages = {21462--21475},

publisher = {OSA},

abstract = {We theoretically investigate a quantum nondemolition (QND) measurement with optical Kerr effect in an ultra-high-Q microtoroidal system. The analytical and numerical results predict that the present QND measurement scheme possesses a high sensitivity, which allows for detecting few photons or even single photons. Ultra-high-Q toroidal microcavity may provide a novel experimental platform to study quantum physics with nonlinear optics at low light levels.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.101.100502,

title = {Fidelity Criterion for Quantum-Domain Transmission and Storage of Coherent States Beyond the Unit-Gain Constraint},

author = {Ryo Namiki and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.101.100502},

doi = {10.1103/PhysRevLett.101.100502},

year  = {2008},

date = {2008-09-01},

journal = {Phys. Rev. Lett.},

volume = {101},

pages = {100502},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yamamoto2008robust,

title = {Robust photonic entanglement distribution by state-independent encoding onto decoherence-free subspace},

author = {Takashi Yamamoto and Kodai Hayashi and {Ş}ahin K Özdemir and Masato Koashi and Nobuyuki Imoto},

url = {https://www.nature.com/articles/nphoton.2008.130},

doi = {10.1038/nphoton.2008.130},

year  = {2008},

date = {2008-07-01},

journal = {Nature Photonics},

volume = {2},

number = {8},

pages = {488},

publisher = {Nature Publishing Group},

note = {press release by JST and Osaka univ.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.78.010307,

title = {Continuous-variable quantum swapping gate between light and atoms},

author = {Tetsushi Takano and Miho Fuyama and Ryo Namiki and Yoshiaki Takahashi},

url = {https://link.aps.org/doi/10.1103/PhysRevA.78.010307},

doi = {10.1103/PhysRevA.78.010307},

year  = {2008},

date = {2008-07-01},

journal = {Phys. Rev. A},

volume = {78},

pages = {010307},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.100.210501,

title = {Generation of High-Fidelity Four-Photon Cluster State and Quantum-Domain Demonstration of One-Way Quantum Computing},

author = {Yuuki Tokunaga and Shin Kuwashiro and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.100.210501},

doi = {10.1103/PhysRevLett.100.210501},

year  = {2008},

date = {2008-05-01},

journal = {Phys. Rev. Lett.},

volume = {100},

pages = {210501},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.77.030302,

title = {Elementary optical gate for expanding an entanglement web},

author = {Toshiyuki Tashima and {Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.77.030302},

doi = {10.1103/PhysRevA.77.030302},

year  = {2008},

date = {2008-03-01},

journal = {Phys. Rev. A},

volume = {77},

pages = {030302},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.99.180503,

title = {Simple and Efficient Quantum Key Distribution with Parametric Down-Conversion},

author = {Yoritoshi Adachi and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.99.180503},

doi = {10.1103/PhysRevLett.99.180503},

year  = {2007},

date = {2007-11-01},

journal = {Phys. Rev. Lett.},

volume = {99},

pages = {180503},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.76.042325,

title = {Teleportation of qubit states through dissipative channels: Conditions for surpassing the no-cloning limit},

author = {{Ş}ahin K Özdemir and Karol Bartkiewicz and Yu-xi Liu and Adam Miranowicz},

url = {https://link.aps.org/doi/10.1103/PhysRevA.76.042325},

doi = {10.1103/PhysRevA.76.042325},

year  = {2007},

date = {2007-10-01},

journal = {Phys. Rev. A},

volume = {76},

pages = {042325},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-9-6-191,

title = {Experimental ancilla-assisted qubit transmission against correlated noise using quantum parity checking},

author = {Takashi Yamamoto and Ryoji Nagase and Junichi Shimamura and {Ş}ahin K Özdemir and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/9/i=6/a=191},

year  = {2007},

date = {2007-06-01},

journal = {New Journal of Physics},

volume = {9},

number = {6},

pages = {191},

abstract = {We report the experimental demonstration of a transmission scheme which has the ability to transmit any state of a photonic qubit over unstabilized optical fibres, regardless of whether the qubit is known, unknown, or entangled to other systems. A high fidelity to the noiseless quantum channel was achieved by adding an ancilla photon after the signal photon within the correlation time of the fibre noise and by performing a measurement which computes the parity. Simplicity, the maintenance-free nature and robustness against path-length mismatches among the nodes make our scheme suitable for multi-user quantum communication networks.},

note = {chosen in IOP Select},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.75.032307,

title = {Selective entanglement breaking},

author = {Yuma Kinoshita and Ryo Namiki and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.75.032307},

doi = {10.1103/PhysRevA.75.032307},

year  = {2007},

date = {2007-03-01},

journal = {Phys. Rev. A},

volume = {75},

pages = {032307},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Miranowicz:07,

title = {Selective truncations of an optical state using projection synthesis},

author = {Adam Miranowicz and {Ş}ahin K Özdemir and Jirí Bajer and Masato Koashi and Nobuyuki Imoto},

url = {http://josab.osa.org/abstract.cfm?URI=josab-24-2-379},

doi = {10.1364/JOSAB.24.000379},

year  = {2007},

date = {2007-02-01},

journal = {J. Opt. Soc. Am. B},

volume = {24},

number = {2},

pages = {379--383},

publisher = {OSA},

abstract = {Selective truncation of the Fock-state expansion of an optical field can be achieved using projection synthesis. The process removes the predetermined Fock states from the input field by conditional measurement and teleportation. We present a scheme to perform projection synthesis based on multiport interferometry. This scheme can be used both as a generalized quantum scissors device that filters out Fock states with photon numbers higher than a predetermined value, and as a quantum punching device that selectively removes specific Fock states, making holes in the Fock-state expansion of the input field.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1367-2630-9-2-043,

title = {A necessary and sufficient condition to play games in quantum mechanical settings},

author = {{Ş}ahin K Özdemir and Junichi Shimamura and Nobuyuki Imoto},

url = {http://stacks.iop.org/1367-2630/9/i=2/a=043},

year  = {2007},

date = {2007-02-01},

journal = {New Journal of Physics},

volume = {9},

number = {2},

pages = {43},

abstract = {Quantum game theory is a multidisciplinary field which combines quantum mechanics with game theory by introducing non-classical resources such as entanglement, quantum operations and quantum measurement. By transferring two-player two-strategy (2 × 2) dilemma containing classical games into the quantum realm, dilemmas can be resolved in quantum pure strategies if entanglement is distributed between the players who use quantum operations. Moreover, players receive the highest sum of payoffs available in the game, which are otherwise impossible in classical pure strategies. Encouraged by the observation of rich dynamics of physical systems with many interacting parties and the power of entanglement in quantum versions of 2 × 2 games, it became generally accepted that quantum versions can be easily extended to N -player situations by simply allowing N -partite entangled states. In this article, however, we show that this is not generally true because the reproducibility of classical tasks in the quantum domain imposes limitations on the type of entanglement and quantum operators. We propose a benchmark for the evaluation of quantum and classical versions of games, and derive the necessary and sufficient conditions for a physical realization. We give examples of entangled states that can and cannot be used, and the characteristics of quantum operators used as strategies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{miranowicz2007,

title = {Quantum Entanglement and Teleportation of Quantum-Dot States in Microcavities},

author = {Adam Miranowicz and {Ş}ahin K Özdemir and Yu-xi Liu and Grzegorz Chimczak and Masato Koashi and Nobuyuki Imoto},

year  = {2007},

date = {2007-01-01},

booktitle = {e-Journal of Surface Science and Nanotechnology},

volume = {5},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sahin2006,

title = {Nuclear Spins in a Nanoscale Device for Quantum Information Processing},

author = {{Ş}ahin K Özdemir and Adam Miranowicz and Tsuyoshi Ota and Go Yusa and Nobuyuki Imoto and Yoshiro Hirayama},

doi = {10.1380/ejssnt.2006.669},

year  = {2006},

date = {2006-12-01},

journal = {e-Journal of Surface Science and Nanotechnology},

volume = {4},

pages = {669-673},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.74.032302,

title = {Efficient-phase-encoding protocols for continuous-variable quantum key distribution using coherent states and postselection},

author = {Ryo Namiki and Takuya Hirano},

url = {https://link.aps.org/doi/10.1103/PhysRevA.74.032302},

doi = {10.1103/PhysRevA.74.032302},

year  = {2006},

date = {2006-09-01},

journal = {Phys. Rev. A},

volume = {74},

pages = {032302},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.74.020301,

title = {Fidelity estimation and entanglement verification for experimentally produced four-qubit cluster states},

author = {Yuuki Tokunaga and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.74.020301},

doi = {10.1103/PhysRevA.74.020301},

year  = {2006},

date = {2006-08-01},

journal = {Phys. Rev. A},

volume = {74},

pages = {020301},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{0953-8984-18-21-S13,

title = {Nanometre-scale nuclear-spin device for quantum information processing},

url = {http://stacks.iop.org/0953-8984/18/i=21/a=S13},

year  = {2006},

date = {2006-05-01},

journal = {Journal of Physics: Condensed Matter},

volume = {18},

number = {21},

pages = {S885},

abstract = {We have developed semiconductor point contact devices in which nuclear spins in a nanoscale region are coherently controlled by all-electrical methods. Different from the standard nuclear-magnetic resonance technique, the longitudinal magnetization of nuclear spins is directly detected by measuring resistance, resulting in ultra-sensitive detection of the microscopic quantity of nuclear spins. All possible coherent oscillations have been successfully demonstrated between two levels from four nuclear spin states of I = 3/2 nuclei. Quantum information processing is discussed based on two fictitious qubits of an I = 3/2 system and methods are described for performing arbitrary logical gates both on one and two qubits. A scheme for quantum state tomography based on M z -detection is also proposed. As the starting point of quantum manipulations, we have experimentally prepared the effective pure states for the I = 3/2 nuclear spin system.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.73.032302,

title = {Cloning and optimal Gaussian individual attacks for a continuous-variable quantum key distribution using coherent states and reverse reconciliation},

author = {Ryo Namiki and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.73.032302},

doi = {10.1103/PhysRevA.73.032302},

year  = {2006},

date = {2006-03-01},

journal = {Phys. Rev. A},

volume = {73},

pages = {032302},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.72.032335,

title = {Probabilistic cloning with supplementary information},

author = {Koji Azuma and Junichi Shimamura and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.72.032335},

doi = {10.1103/PhysRevA.72.032335},

year  = {2005},

date = {2005-09-01},

journal = {Phys. Rev. A},

volume = {72},

pages = {032335},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.72.024301,

title = {Security of continuous-variable quantum cryptography using coherent states: Decline of postselection advantage},

author = {Ryo Namiki and Takuya Hirano},

url = {https://link.aps.org/doi/10.1103/PhysRevA.72.024301},

doi = {10.1103/PhysRevA.72.024301},

year  = {2005},

date = {2005-08-01},

journal = {Phys. Rev. A},

volume = {72},

pages = {024301},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.95.040503,

title = {Faithful Qubit Distribution Assisted by One Additional Qubit against Collective Noise},

author = {Takashi Yamamoto and Junichi Shimamura and {Ş}ahin K Özdemir and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.95.040503},

doi = {10.1103/PhysRevLett.95.040503},

year  = {2005},

date = {2005-07-01},

journal = {Phys. Rev. Lett.},

volume = {95},

pages = {040503},

publisher = {American Physical Society},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.71.030301,

title = {Simple experimental scheme of preparing a four-photon entangled state for the teleportation-based realization of a linear optical controlled-NOT gate},

author = {Yuuki Tokunaga and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.71.030301},

doi = {10.1103/PhysRevA.71.030301},

year  = {2005},

date = {2005-03-01},

journal = {Phys. Rev. A},

volume = {71},

pages = {030301},

publisher = {American Physical Society},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.71.012314,

title = {Threshold quantum cryptography},

author = {Yuuki Tokunaga and Tatsuaki Okamoto and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.71.012314},

doi = {10.1103/PhysRevA.71.012314},

year  = {2005},

date = {2005-01-01},

journal = {Phys. Rev. A},

volume = {71},

pages = {012314},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1142/S0219749905001262,

title = {SECURITY OF QUANTUM KEY DISTRIBUTION WITH STRONG PHASE-REFERENCE PULSE},

author = {Masato Koashi},

url = {https://www.worldscientific.com/doi/abs/10.1142/S0219749905001262},

doi = {10.1142/S0219749905001262},

year  = {2005},

date = {2005-01-01},

journal = {International Journal of Quantum Information},

volume = {03},

number = {supp01},

pages = {75-86},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{OZDEMIR2004218,

title = {Dynamics of a discoordination game with classical and quantum correlations},

author = {{Ş}ahin K Özdemir and Junichi Shimamura and Fumiaki Morikoshi and Nobuyuki Imoto},

url = {http://www.sciencedirect.com/science/article/pii/S0375960104015154},

doi = {https://doi.org/10.1016/j.physleta.2004.10.055},

issn = {0375-9601},

year  = {2004},

date = {2004-12-01},

journal = {Physics Letters A},

volume = {333},

number = {3},

pages = {218 - 231},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.70.042308,

title = {Kraus representation of a damped harmonic oscillator and its application},

author = {Yu-xi Liu and {Ş}ahin K Özdemir and Adam Miranowicz and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevA.70.042308},

doi = {10.1103/PhysRevA.70.042308},

year  = {2004},

date = {2004-10-01},

journal = {Phys. Rev. A},

volume = {70},

pages = {042308},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.93.120501,

title = {Unconditional Security of Coherent-State Quantum Key Distribution with a Strong Phase-Reference Pulse},

author = {Masato Koashi},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.93.120501},

doi = {10.1103/PhysRevLett.93.120501},

year  = {2004},

date = {2004-09-01},

journal = {Phys. Rev. Lett.},

volume = {93},

pages = {120501},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{SHIMAMURA200420,

title = {Entangled states that cannot reproduce original classical games in their quantum version},

author = {Junichi Shimamura and {Ş}ahin K Özdemir and Fumiaki Morikoshi and Nobuyuki Imoto},

url = {http://www.sciencedirect.com/science/article/pii/S0375960104007790},

doi = {https://doi.org/10.1016/j.physleta.2004.06.006},

issn = {0375-9601},

year  = {2004},

date = {2004-07-01},

journal = {Physics Letters A},

volume = {328},

number = {1},

pages = {20 - 25},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.69.032316,

title = {Unconditional security of the Bennett 1992 quantum key-distribution protocol over a lossy and noisy channel},

author = {Kiyoshi Tamaki and Norbert Lütkenhaus},

url = {https://link.aps.org/doi/10.1103/PhysRevA.69.032316},

doi = {10.1103/PhysRevA.69.032316},

year  = {2004},

date = {2004-03-01},

journal = {Phys. Rev. A},

volume = {69},

pages = {032316},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{0305-4470-37-15-010,

title = {Exciton entanglement in two coupled semiconductor microcrystallites},

author = {Yu-xi Liu and {Ş}ahin K Özdemir and Adam Miranowicz and Masato Koashi and Nobuyuki Imoto},

url = {http://stacks.iop.org/0305-4470/37/i=15/a=010},

year  = {2004},

date = {2004-03-01},

journal = {Journal of Physics A: Mathematical and General},

volume = {37},

number = {15},

pages = {4423},

abstract = {Entanglement of the excitonic states in the system of two coupled semiconductor microcrystallites, whose sizes are much larger than the Bohr radius of the exciton in the bulk semiconductor but smaller than the relevant optical wavelength, is quantified in terms of the entropy of entanglement. It is observed that the nonlinear interaction between excitons increases the maximum values of the entropy of entanglement more than that of the linear coupling model. Therefore, a system of two coupled microcrystallites can be used as a good source of entanglement with fixed exciton number. The relationship between the entropy of entanglement and the population imbalance of two microcrystallites is numerically shown and the uppermost envelope function for them is estimated by applying the Jaynes principle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.69.022309,

title = {Monogamy of quantum entanglement and other correlations},

author = {Masato Koashi and Andreas Winter},

url = {https://link.aps.org/doi/10.1103/PhysRevA.69.022309},

doi = {10.1103/PhysRevA.69.022309},

year  = {2004},

date = {2004-02-01},

journal = {Phys. Rev. A},

volume = {69},

pages = {022309},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{shimamura,

title = {Quantum and classical correlations between players in game theory},

author = {Junichi Shimamura and {Ş}ahin K Özdemir and Fumiaki Morikoshi and Nobuyuki Imoto},

year  = {2004},

date = {2004-01-01},

journal = {International Journal of Quantum Information},

volume = {2},

number = {01},

pages = {79--89},

publisher = {World Scientific doi = 10.1142/S0219749904000092},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{OZDEMIR2004104,

title = {Quantum advantage does not survive in the presence of a corrupt source: optimal strategies in simultaneous move games},

author = {{Ş}ahin K Özdemir and Junichi Shimamura and Nobuyuki Imoto},

url = {http://www.sciencedirect.com/science/article/pii/S0375960104004219},

doi = {https://doi.org/10.1016/j.physleta.2004.03.042},

issn = {0375-9601},

year  = {2004},

date = {2004-01-01},

journal = {Physics Letters A},

volume = {325},

number = {2},

pages = {104 - 111},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sahin2003,

title = {Quantum state generation and entanglement manipulation using linear optics},

author = {{Ş}ahin K Özdemir and Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

year  = {2003},

date = {2003-09-01},

journal = {Turkish Journal of Physics},

volume = {27},

pages = {459 - 479},

keywords = {multi-photon interference},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.90.167904,

title = {Unconditionally Secure Key Distribution Based on Two Nonorthogonal States},

author = {Kiyoshi Tamaki and Masato Koashi and Nobuyuki Imoto},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.90.167904},

doi = {10.1103/PhysRevLett.90.167904},

year  = {2003},

date = {2003-04-01},

journal = {Phys. Rev. Lett.},

volume = {90},

pages = {167904},

publisher = {American Physical Society},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Yamamoto2003,

title = {Experimental extraction of an entangled photon pair from two identically decohered pairs},

author = {Takashi Yamamoto and Masato Koashi and {Ş}ahin K Özdemir and Nobuyuki Imoto},

url = {https://www.nature.com/articles/nature01358},

doi = {10.1038/nature01358},

year  = {2003},

date = {2003-01-23},

journal = {Nature},

volume = {421},

pages = {343–346},

keywords = {entanglement},

pubstate = {published},

tppubtype = {article}

}

@article{Yamamoto2002,

title = {Polarization entangled W state using parametric down-conversion},

author = {Takashi Yamamoto and Kiyoshi Tamaki and Masato Koashi and Nobuyuki Imoto},

url = {https://doi.org/10.1103/PhysRevA.66.064301},

doi = {10.1103/PhysRevA.66.064301},

year  = {2002},

date = {2002-12-06},

journal = {Phys. Rev. A},

volume = {66},

pages = {064301 },

keywords = {entanglement},

pubstate = {published},

tppubtype = {article}

}

@article{Yamamoto2001,

title = {Concentration and purification scheme for two partially entangled photon pairs},

author = {Takashi Yamamoto and Masato Koashi and Nobuyuki Imoto},

url = {https://doi.org/10.1103/PhysRevA.64.012304},

doi = {10.1103/PhysRevA.64.012304},

year  = {2001},

date = {2001-06-04},

journal = {Phys. Rev. A},

volume = {64},

pages = {012304},

keywords = {entanglement},

pubstate = {published},

tppubtype = {article}

}

@article{Koashi2001,

title = {Probabilistic manipulation of entangled photons},

author = {Masato Koashi and Takashi Yamamoto and Nobuyuki Imoto},

url = {https://doi.org/10.1103/PhysRevA.63.030301},

doi = {10.1103/PhysRevA.63.030301},

year  = {2001},

date = {2001-02-12},

journal = {Phys. Rev. A},

volume = {63},

number = {030301(R)},

keywords = {entanglement, multi-photon interference},

pubstate = {published},

tppubtype = {article}

}