Publications (95)
Observables suitable for restricting the fidelity to multipartite maximally entangled states
Koji Nagata, Masato Koashi, Nobuyuki Imoto
Efficient simulation of quantum error correction under coherent error based on non-unitary free-fermionic formalism
Yasunari Suzuki, Keisuke Fujii, Masato Koashi
Appropriate probe condition for absorption imaging of ultracold $^6$Li atoms
Munekazu Horikoshi, Aki Ito, Takuya Ikemachi +3
Boosting up quantum key distribution by learning statistics of practical single photon sources
Yoritoshi Adachi, Takashi Yamamoto, Masato Koashi +1
Tight bound on coherent-state-based entanglement generation over lossy channels
Koji Azuma, Naoya Sota, Masato Koashi +1
Monogamy of entanglement and other correlations
Masato Koashi, Andreas Winter
Teleportation cost and hybrid compression of quantum signals
Masato Koashi, Nobuyuki Imoto
Theory of spin-2 Bose-Einstein condensates: spin-correlations, magnetic response, and excitation spectra
Masahito Ueda, Masato Koashi
Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair
Kazuhiro Yokota, Takashi Yamamoto, Masato Koashi +1
Optimal entanglement generation for efficient hybrid quantum repeaters
Naoya Sota, Koji Azuma, Ryo Namiki +4
Dynamics of evaporative cooling in magnetically trapped atomic hydrogen
Makoto Yamashita, Masato Koashi, Tetsuya Mukai +2
Rigorous calibration method for photon-number statistics
Masahiro Kumazawa, Toshihiko Sasaki, Masato Koashi
Pulse-mode quantum projection synthesis: Effects of mode mismatch on optical state truncation and preparation
Sahin Kaya Ozdemir, Adam Miranowicz, Masato Koashi +1
Unconditionally Secure Key Distribution Based on Two Nonorthogonal States
Kiyoshi Tamaki, Masato Koashi, Nobuyuki Imoto
Finite-key analysis for quantum key distribution with weak coherent pulses based on Bernoulli sampling
Shun Kawakami, Toshihiko Sasaki, Masato Koashi
Polarization insensitive frequency conversion for an atom-photon entanglement distribution via a telecom network
Rikizo Ikuta, Toshiki Kobayashi, Tetsuo Kawakami +8
Security of quantum key distribution with discrete rotational symmetry
Masato Koashi
Does "quantum nonlocality without entanglement" have quantum origin?
Masato Koashi, Koji Azuma, Shinya Nakamura +1
Robust photonic entanglement distribution via state-independent encoding onto decoherence-free subspace
Takashi Yamamoto, Kodai Hayashi, Sahin Kaya Ozdemir +2
Quantum catalysis of information
Koji Azuma, Masato Koashi, Nobuyuki Imoto
Quantum information is incompressible without errors
Masato Koashi, Nobuyuki Imoto
Exact Eigenstates and Magnetic Response of Spin-1 and Spin-2 Vectorial Bose-Einstein Condensates
Masato Koashi, Masahito Ueda
Frequency-domain Hong-Ou-Mandel interference
Toshiki Kobayashi, Rikizo Ikuta, Shuto Yasui +6
Optical qubit generation by state truncation using an experimentally feasible scheme
Sahin Kaya Ozdemir, Adam Miranowicz, Masato Koashi +1
Selective truncations of an optical state using projection synthesis
Adam Miranowicz, Sahin Kaya Ozdemir, Jiri Bajer +2
Quantum repeaters and computation by a single module
Koji Azuma, Hitoshi Takeda, Masato Koashi +1
Optimal local expansion of W states using linear optics and Fock states
Rikizo Ikuta, Toshiyuki Tashima, Takashi Yamamoto +2
Quantum-scissors device for optical state truncation: A proposal for practical realization
Sahin Kaya Ozdemir, Adam Miranowicz, Masato Koashi +1
Complementarity, distillable secret key, and distillable entanglement
Masato Koashi
A distributed architecture for scalable quantum computation with realistically noisy devices
Keisuke Fujii, Takashi Yamamoto, Masato Koashi +1
Exciton entanglement in two coupled semiconductor microcrystallites
Yu-xi Liu, Sahin K. Ozdemir, Adam Miranowicz +2
Efficient unitary designs with nearly time-independent Hamiltonian dynamics
Yoshifumi Nakata, Christoph Hirche, Masato Koashi +1
Entanglement cost of generalised measurements
Richard Jozsa, Masato Koashi, Noah Linden +4
Matter-field theory of the Casimir force
Masato Koashi, Masahito Ueda
Experimental demonstration of robust entanglement distribution over reciprocal noisy channels assisted by a counter-propagating classical reference light
Rikizo Ikuta, Shota Nozaki, Takashi Yamamoto +2
High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectors
Rikizo Ikuta, Hiroshi Kato, Yoshiaki Kusaka +9
Secure quantum key distribution with an uncharacterized source
Masato Koashi, John Preskill
A low-noise frequency down-conversion to the telecommunication band for a quantum communication based on NV centers in diamond
Rikizo Ikuta, Toshiki Kobayashi, Shuto Yasui +9
Simple security proof of quantum key distribution via uncertainty principle
Masato Koashi
Refined security proof of the round-robin differential phase shift quantum key distribution and its improved performance in the finite-sized case
Takaya Matsuura, Toshihiko Sasaki, Masato Koashi
Quantum key distribution with an efficient countermeasure against correlated intensity fluctuations in optical pulses
Ken-ichiro Yoshino, Mikio Fujiwara, Kensuke Nakata +7
High-fidelity entanglement swapping and generation of three-qubit GHZ state using asynchronous telecom photon pair sources
Yoshiaki Tsujimoto, Motoki Tanaka, Nobuo Iwasaki +7
Efficient decoherence-free entanglement distribution over lossy quantum channels
Rikizo Ikuta, Yohei Ono, Toshiyuki Tashima +3
Fidelity criterion for quantum-domain transmission and storage of coherent states beyond unit-gain constraint
Ryo Namiki, Masato Koashi, Nobuyuki Imoto
Wide-band quantum interface for visible-to-telecommunication wavelength conversion
Rikizo Ikuta, Yoshiaki Kusaka, Tsuyoshi Kitano +4
Optimal two-qubit tomography based on local and global measurements: Maximal robustness against errors as described by condition numbers
Adam Miranowicz, Karol Bartkiewicz, Jan Perina +3
Unconditional security of coherent-state-based differential phase shift quantum key distribution protocol with block-wise phase randomization
Kiyoshi Tamaki, Masato Koashi, Go Kato
All-optical production of a superfluid Bose-Fermi mixture of $^6$Li and $^7$Li
Takuya Ikemachi, Aki Ito, Yukihito Aratake +4
Generating a state $t$-design by diagonal quantum circuits
Yoshifumi Nakata, Masato Koashi, Mio Murao
Fundamental limit to Qubit Control with Coherent Field
Kazuhiro Igeta, Nobuyuki Imoto, Masato Koashi
Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon level
Rikizo Ikuta, Toshiki Kobayashi, Hiroshi Kato +9
Security of differential quadrature phase shift quantum key distribution
Shun Kawakami, Toshihiko Sasaki, Masato Koashi
Quantum nonlocality without entanglement in a pair of qubits
Masato Koashi, Fumitaka Takenaga, Takashi Yamamoto +1
Selective entanglement breaking
Yuma Kinoshita, Ryo Namiki, Takashi Yamamoto +2
Dynamics of entanglement for coherent excitonic states in a system of two coupled quantum dots and cavity QED
Yu-xi Liu, S. K. Ozdemir, Masato Koashi +1
Cloning and Optimal Gaussian individual attacks for continuous-variable quantum key distribution using coherent states and reverse reconciliation
Ryo Namiki, Masato Koashi, Nobuyuki Imoto
Generation of high-fidelity four-photon cluster state and quantum-domain demonstration of one-way quantum computing
Yuuki Tokunaga, Shin Kuwashiro, Takashi Yamamoto +2
Compressibility of Mixed-State Signals
Masato Koashi, Nobuyuki Imoto
Efficient quantum key distribution with practical sources and detectors
Masato Koashi
Heralded single excitation of atomic ensemble via solid-state-based telecom photon detection
Rikizo Ikuta, Toshiki Kobayashi, Kenichiro Matsuki +7
Experimental quantum key distribution without monitoring signal disturbance
Hiroki Takesue, Toshihiko Sasaki, Kiyoshi Tamaki +1
An elementary optical gate for expanding entanglement web
Toshiyuki Tashima, Sahin Kaya Ozdemir, Takashi Yamamoto +2
Extracting an entangled photon pair from collectively decohered pairs at a telecommunication wavelength
Yoshiaki Tsujimoto, Yukihiro Sugiura, Makoto Ando +5
Non-classical two-photon interference between independent telecom light pulses converted by difference-frequency generation
Rikizo Ikuta, Toshiki Kobayashi, Hiroshi Kato +9
Polarization Entangled W State using Parametric Down-Conversion
Takashi Yamamoto, Kiyoshi Tamaki, Masato Koashi +1
Mach-Zehnder interferometer using frequency-domain beamsplitter
Toshiki Kobayashi, Daisuke Yamazaki, Kenichiro Matsuki +7
Demonstration of local expansion toward large-scale entangled webs
Toshiyuki Tashima, Tsuyoshi Kitano, Sahin Kaya Ozdemir +3
An optical fusion gate for W-states
Sahin Kaya Ozdemir, Eiji Matsunaga, Toshiyuki Tashima +3
Local expansion of photonic W state using a polarization dependent beamsplitter
Toshiyuki Tashima, Sahin Kaya Ozdemir, Takashi Yamamoto +2
A Concentration/Purification Scheme for Two Partially Entangled Photon Pairs
Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto
Security of the Bennett 1992 quantum-key distribution against individual attack over a realistic channel
Kiyoshi Tamaki, Masato Koashi, Nobuyuki Imoto
Quantum key distribution protocols with slow basis choice
Toshihiko Sasaki, Kiyoshi Tamaki, Masato Koashi
Probabilistic cloning with supplementary information
Koji Azuma, Junichi Shimamura, Masato Koashi +1
Size-dependent decoherence of excitonic states in semiconductor microcrystallites
Yu-xi Liu, A. Miranowicz, S. K. Ozdemir +2
Quantum cloning with nonlocal assistance: Complement of Jozsa's stronger no-cloning theorem
Koji Azuma, Masato Koashi, Hosho Katsura +1
Entangled webs: Tight bound for symmetric sharing of entanglement
Masato Koashi, Vladimir Buzek, Nobuyuki Imoto
Ground-state thermodynamic quantities of homogeneous spin-$1/2$ fermions from the BCS region to the unitarity limit
Munekazu Horikoshi, Masato Koashi, Hiroyuki Tajima +2
Optimization of evaporative cooling towards a large number of Bose-Einstein condensed atoms
Makoto Yamashita, Masato Koashi, Tetsuya Mukai +3
Error exponents for entanglement concentration
Masahito Hayashi, Masato Koashi, Keiji Matsumoto +2
Simple and efficient quantum key distribution with parametric down-conversion
Yoritoshi Adachi, Takashi Yamamoto, Masato Koashi +1
Deterministic entanglement concentration
Fumiaki Morikoshi, Masato Koashi
What is Possible Without Disturbing Partially Known Quantum States?
Masato Koashi, Nobuyuki Imoto
Optimal Gaussian $N$-to-$M$ cloning with linear optics and Gaussian cloning of known-phase coherent states
Ryo Namiki, Masato Koashi, Nobuyuki Imoto
Universal gates for transforming multipartite entangled Dicke states
Toshiki Kobayashi, Rikizo Ikuta, Sahin Kaya Ozdemir +4
A security proof of the round-robin differential phase shift quantum key distribution protocol based on the signal disturbance
Toshihiko Sasaki, Masato Koashi
Experimental ancilla-assisted qubit transmission against correlated noise using quantum parity checking
Takashi Yamamoto, Ryoji Nagase, Junichi Shimamura +3
Probabilistic manipulation of entangled photons
Masato Koashi, Takashi Yamamoto, Nobuyuki Imoto
Local transformation of two EPR photon pairs into a three-photon W state
Toshiyuki Tashima, Tetsuroh Wakatsuki, Sahin Kaya Ozdemir +3
Security of entanglement-based quantum key distribution with practical detectors
Masato Koashi, Yoritoshi Adachi, Takashi Yamamoto +1
A high visibility Hong-Ou-Mandel interference via a time-resolved coincidence measurement
Yoshiaki Tsujimoto, Yukihiro Sugiura, Motoki Tanaka +9
Unconditional security of the Bennett 1992 quantum key-distribution scheme with strong reference pulse
Kiyoshi Tamaki, Norbert Lütkenhaus, Masato Koashi +1
Configuration of separability and tests for multipartite entanglement in Bell-type experiments
Koji Nagata, Masato Koashi, Nobuyuki Imoto
Realization of symmetric sharing of entanglement in semiconductor microcrystallites coupled by a cavity field
Yu-xi Liu, Adam Miranowicz, Masato Koashi +1
Robustness of quantum communication based on a decoherence-free subspace using a counter-propagating weak coherent light pulse
Hidetoshi Kumagai, Takashi Yamamoto, Masato Koashi +1
Unconditional security of coherent-state quantum key distribution with strong phase-reference pulse
Masato Koashi