Toshihiko Sasaki

J-GLOBAL         Last updated: May 9, 2019 at 12:11
Toshihiko Sasaki
Alternative names
Photon Science Center of the University of Tokyo
The University of Tokyo
Photon Science Center of the University of Tokyo
Job title

Research Areas


Published Papers

Nagao Kurumiko, Horikiri Tomoyuki, Sasaki Toshihiko
PHYSICAL REVIEW A   99(4)    Apr 2019   [Refereed]
Matsuura Takaya, Sasaki Toshihiko, Koashi Masato
PHYSICAL REVIEW A   99(4)    Apr 2019   [Refereed]
Masahiro Kumazawa, Toshihiko Sasaki, and Masato Koashi
Optics Express   27(4) 5297-5313   Feb 2019   [Refereed]
Yoshino Ken-ichiro, Fujiwara Mikio, Nakata Kensuke, Sumiya Tatsuya, Sasaki Toshihiko, Takeoka Masahiro, Sasaki Masahide, Tajima Akio, Koashi Masato, Tomita Akihisa
NPJ QUANTUM INFORMATION   4    Feb 2018   [Refereed]
Mizutani Akihiro, Sasaki Toshihiko, Kato Go, Takeuchi Yuki, Tamaki Kiyoshi
QUANTUM SCIENCE AND TECHNOLOGY   3(1)    Jan 2018   [Refereed]
Kawakami Shun, Sasaki Toshihiko, Koashi Masato
PHYSICAL REVIEW A   96(1)    Jul 2017   [Refereed]
Sasaki Toshihiko, Koashi Masato
QUANTUM SCIENCE AND TECHNOLOGY   2(2)    Jun 2017   [Refereed]
Shun Kawakami, Toshihiko Sasaki, Masato Koashi
Phys. Rev. A 94   94 022332   Aug 2016   [Refereed]
One of the simplest methods for implementing quantum key distribution over
fiber-optic communication is the Bennett-Brassard 1984 protocol with phase
encoding (PE-BB84 protocol), in which the sender uses phase modulation over
double pulses from a ...
Hiroki Takesue, Toshihiko Sasaki, Kiyoshi Tamaki, Masato Koashi
Nature Photonics   9 827-831   Aug 2015   [Refereed]
Since the invention of Bennett-Brassard 1984 (BB84) protocol, many quantum
key distribution (QKD) protocols have been proposed and some protocols are
operated even in field environments. One of the striking features of QKD is
that QKD protocols ar...
Sasaki T, Yamamoto Y, Koashi M
Nature   509(7501) 475-478   May 2014   [Refereed]
Tatsuya Morita, Toshihiko Sasaki, Izumi Tsutsui
Prog. Theor. Exp. Phys.   2013 053A02   May 2013   [Refereed]
We present a complex probability measure relevant for double (pairs of)
states in quantum mechanics, as an extension of the standard probability
measure for single states that underlies Born's statistical rule. When the
double states are treated a...
Toshihiko Sasaki, Tsubasa Ichikawa, Izumi Tsutsui
Phys. Rev. A   87 052313   May 2013   [Refereed]
Entanglement is known to be a relative notion, defined with respect to the
choice of physical observables to be measured (i.e., the measurement setup
used). This implies that, in general, the same state can be both separable and
entangled for diff...
Toshihiko Sasaki, Tsubasa Ichikawa, Izumi Tsutsui
Journal of the Physical Society of Japan   81 064005   May 2012   [Refereed]
We show that the various intermediate states appearing in the process of
one-way computation at a given step of measurement are all equivalent modulo
local unitary transformations. This implies, in particular, that all those
intermediate states sh...
Toshihiko Sasaki, Tsubasa Ichikawa, Izumi Tsutsui
Phys. Rev. A   83 012113   Jan 2011   [Refereed]
We present a general criterion for entanglement of N indistinguishable
particles decomposed into arbitrary s subsystems based on the unambiguous
measurability of correlation. Our argument provides a unified viewpoint on the
entanglement of indisti...
Tsubasa Ichikawa, Toshihiko Sasaki, Izumi Tsutsui
J. Math. Phys.   51 062202   Mar 2010   [Refereed]
We present a criterion of separability for arbitrary s partitions of
N-particle fermionic pure states. We show that, despite the superficial
non-factorizability due to the antisymmetry required by the
indistinguishability of the particles, the sta...
Tsubasa Ichikawa, Toshihiko Sasaki, Izumi Tsutsui
Phys. Rev. A   79 052307   May 2009   [Refereed]
We present a family of entanglement measures R_m which act as indicators for
separability of n-qubit quantum states into m subsystems for arbitrary 2 \leq m
\leq n. The measure R_m vanishes if the state is separable into m subsystems,
and for m = ...
Tsubasa Ichikawa, Toshihiko Sasaki, Izumi Tsutsui, Nobuhiro Yonezawa
Phys. Rev. A   78 052105   Sep 2008   [Refereed]
Entanglement of multipartite systems is studied based on exchange symmetry
under the permutation group S_N. With the observation that symmetric property
under the exchange of two constituent states and their separability are
intimately linked, we ...


Akihiro Mizutani, Toshihiko Sasaki, Go Kato, Yuki Takeuchi, Kiyoshi Tamaki
   Apr 2017
We show the information-theoretic security proof of the
differential-phase-shift (DPS) quantum key distribution (QKD) protocol based on
the complementarity approach [arXiv:0704.3661 (2007)]. Our security proof
provides a slightly better key genera...
Toshihiko Sasaki, Masato Koashi
   Jan 2017
The round-robin differential phase shift (RRDPS) quantum key distribution
(QKD) protocol is a unique quantum key distribution protocol whose security has
not been understood through an information-disturbance trade-off relation, and
a sufficient a...
Shun Kawakami, Toshihiko Sasaki, Masato Koashi
   Jan 2017
An essential step in quantum key distribution is the estimation of parameters
related to the leaked amount of information, which is usually done by sampling
of the communication data. When the data size is finite, the final key rate
depends on how...
Toshihiko Sasaki, Kiyoshi Tamaki, Masato Koashi
   Apr 2016
Many quantum key distribution (QKD) protocols require random choice of
measurement basis for each pulse or each train of pulses. In some QKD
protocols, such as the Round-Robin Differential Phase Shift (RRDPS) QKD
protocol, this requirement is a bi...
佐々木 寿彦
応用物理   85(2) 105-108   Feb 2016

Conference Activities & Talks

Feedforward attack in decoy-state quantum key distribution
Toshihiko Sasaki
QCrypt2018   26 Aug 2018   
Rigorous calibration method for photon-number statistics
Toshihiko Sasaki
CQIS2018   11 Apr 2018   
Quantum Key Distribution Protocol with Slow Basis Change
Toshihiko Sasaki, Kiyoshi Tamaki, Masato Koashi
QCrypt2016   13 Sep 2016   
Quantum key distribution protocol without monitoring signal disturbance [Invited]
Toshihiko Sasaki
EMN MEETING ON QUANTUM 2016   9 Apr 2016   
Round-robin differential phase-shift quantum key distribution protocol with threshold detectors
Toshihiko Sasaki
QCrypt2015   Sep 2015   
New scheme of quantum key distribution: avoiding information leak rather than detecting [Invited]
Toshihiko Sasaki
Quantum Science Symposium-2015   Sep 2015   
Annual conference of Chinese Asscociation for cryptographic research, quantum cryprography division [Invited]
Toshihiko Sasaki
Annual conference of Chinese Asscociation for cryptographic research, quantum cryprography division   Aug 2015   
Entanglement measures for intermediate separability
T. Sasaki, T. Ichikawa, I. Tsutsui
Summer School on Decoherence Entanglement and Entropy   Jul 2009   

Association Memberships