Takahashi, Hiroki, Wakui, Kentaro, Suzuki, Shigenari, Takeoka, Masahiro, Hayasaka, Kazuhiro, Furusawa, Akira, ...
We propose and demonstrate a novel method to generate a large-amplitude coherent-state superposition (CSS) via ancilla-assisted photon-subtraction. The ancillary mode induces quantum interference of...
Tanaka, Akihiro, Fujiwara, Mikio, Nam, Sae Woo, Nambu, Yoshihiro, Takahashi, Seigo, Maeda, Wakako, ...
We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on...
Takeoka, Masahiro, Takahashi, Hiroki, Sasaki, Masahide
Theoretical analysis is given for a two-photon subtraction from a continuous wave (CW) squeezed vacuum with finite time separation between two detection events. In the CW photon subtraction process,...
Temporally multiplexed superposition states of continuous variables (2008)
Sasaki, Masahide, Takeoka, Masahiro, Takahashi, Hiroki
We study non-Gaussian states generated by two-photon subtraction from a cw squeezed light source. In a cw scheme one can subtract two photons from the source with a designated time separation and can...
Takeoka, Masahiro, Sasaki, Masahide
We address the limit of the Gaussian operations and classical communication in the problem of quantum state discrimination. We show that the optimal Gaussian strategy for the discrimination of the...
Unambiguous discrimination among oracle operators (2007)
Chefles, Anthony, Kitagawa, Akira, Takeoka, Masahiro, Sasaki, Masahide, Twamley, Jason
We address the problem of unambiguous discrimination among oracle operators. The general theory of unambiguous discrimination among unitary operators is extended with this application in mind. We...
Conditional generation of an arbitrary superposition of coherent states (2007)
Takeoka, Masahiro, Sasaki, Masahide
We present a scheme to conditionally generate an arbitrary superposition of a pair of coherent states from a squeezed vacuum by means of the modified photon subtraction where a coherent state ancilla...
Entanglement quantification with Fisher information (2006)
Kitagawa, Akira, Takeoka, Masahiro, Sasaki, Masahide, Chefles, Anthony
We show that the Fisher information associated with entanglement-assisted coding has a monotonic relationship with the logarithmic negativity, an important entanglement measure, for certain classes...
Binary projective measurement via linear optics and photon counting (2006)
Takeoka, Masahiro, Sasaki, Masahide, Lütkenhaus, Norbert
We investigate the implementation of binary projective measurements with linear optics. This problem can be viewed as a single-shot discrimination of two orthogonal pure quantum states. We show that...
7 dB quadrature squeezing at 860 nm with periodically-poled KTiOPO4 (2006)
Suzuki, Shigenari, Yonezawa, Hidehiro, Kannari, Fumihiko, Sasaki, Masahide, Furusawa, Akira
We observed -7.2 dB quadrature squeezing at 860 nm by using a sub-threshold continuous-wave pumped optical parametric oscillator with a periodically-poled KTiOPO4 crystal as a nonlinear optical...
Kitagawa, Akira, Takeoka, Masahiro, Sasaki, Masahide, Chefles, Anthony
We consider the problem of evaluating the entanglement of non-Gaussian mixed states generated by photon subtraction from entangled squeezed states. The entanglement measures we use are the negativity...
Fujiwara, Mikio, Sasaki, Masahide
We demonstrate multiphoton discrimination at telecom wavelength with the readout frequency of 40 Hz by charge integration photon detector (CIPD). The CIPD consists of an InGaAs pin photodiode and a...
Suzuki, Shigenari, Takeoka, Masahiro, Sasaki, Masahide, Andersen, Ulrik L., Kannari, Fumihiko
We present a simple protocol to purify a coherent-state superposition that has undergone a linear lossy channel. The scheme constitutes only a single beam splitter and a homodyne detector, and thus...
Akiba, Makoto, Fujiwara, Mikio, Sasaki, Masahide
A highly sensitive photodetection system with a detection limit of 1 photon/s was developed. This system uses a commercially available 200-mm-diameter silicon avalanche photodiode (APD) and an...
Kitagawa, Akira, Takeoka, Masahiro, Wakui, Kentaro, Sasaki, Masahide
We study the measurement-induced non-Gaussian operation on the single- and two-mode \textit{Gaussian} squeezed vacuum states with beam splitters and on-off type photon detectors, with which...
Multiphoton discrimination at telecom wavelength with charge integration photon detector (2005)
Fujiwara, Mikio, Sasaki, Masahide
We present a charge integration photon detector (CIPD) that enables the efficient measurement of photon number states at the telecom-fiber wavelengths with a quantum efficiency of 80% and a...
Implementation of projective measurements with linear optics and continuous photon counting (2004)
Takeoka, Masahiro, Sasaki, Masahide, Van Loock, Peter, Lütkenhaus, Norbert
We investigate the possibility of implementing a given projection measurement using linear optics and arbitrarily fast feedforward based on the continuous detection of photons. In particular, we...
Mizuno, Jun, Wakui, Kentaro, Furusawa, Akira, Sasaki, Masahide
We have experimentally realized the scheme initially proposed as quantum dense coding with continuous variables [Ban, J. Opt. B \textbf{1}, L9 (1999), and Braunstein and Kimble, \pra\textbf{61},...
Exceeding classical capacity limit in quantum optical channel (2003)
Fujiwara, Mikio, Takeoka, Masahiro, Mizuno, Jun, Sasaki, Masahide
The amount of information transmissible through a communications channel is determined by the noise characteristics of the channel and by the quantities of available transmission resources. In...
Unambiguous quantum state filtering (2003)
Takeoka, Masahiro, Ban, Masashi, Sasaki, Masahide
In this paper, we consider the generalized measurement where one particular quantum signal is unambiguously extracted from a set of non-commutative quantum signals and the other signals are filtered...
The Quantumness of a Set of Quantum States (2003)
Fuchs, Christopher A., Sasaki, Masahide
This article is an introduction to quant-ph/0302092. We propose to quantify how "quantum" a set of quantum states is. The quantumness of a set is the worst-case difficulty of transmitting the states...
Fuchs, Christopher A., Sasaki, Masahide
In this paper we propose a general method to quantify how "quantum" a set of quantum states is. The idea is to gauge the quantumness of the set by the worst-case difficulty of transmitting the states...
Experimental Demonstration of Quantum Source Coding (2003)
Mitsumori, Yasuyoshi, Vaccaro, Joan Alfina, Barnett, Stephen M., Andersson, Erika, Hasegawa, A.tsushi, Takeoka, Masahiro, ...
We report an experimental demonstration of Schumacher's quantum noiseless coding theorem. Our experiment employs a sequence of single photons, each of which represents three qubits in terms of eight...
Experimental Demonstration of Quantum Source Coding (2003)
Mitsumori, Yasuyoshi, Vaccaro, Joan Alfina, Barnett, Stephen M., Andersson, Erika, Hasegawa, A.tsushi, Takeoka, Masahiro, ...
We report an experimental demonstration of Schumacher's quantum noiseless coding theorem. Ourexperiment employs a sequence of single photons, each of which represents three qubits in terms ofeight...
Experimental Demonstration of Quantum Source Coding (2003)
Mitsumori, Yasuyoshi, Vaccaro, Joan Alfina, Barnett, Stephen M., Andersson, Erika, Hasegawa, A.tsushi, Takeoka, Masahiro, ...
We report an experimental demonstration of Schumacher's quantum noiseless coding theorem. Our experiment employs a sequence of single photons, each of which represents three qubits in terms of eight...
Practical scheme for the optimal measuremnet in quantum interferometric devices (2002)
Takeoka, Masahiro, Ban, Masashi, Sasaki, Masahide
We apply a Kennedy-type detection scheme, which was originally proposed for a binary communications system, to interferometric sensing devices. We show that the minimum detectable perturbation of the...
Optimal parameter estimation of a depolarizing channel (2002)
Ban, Masashi, Barnett, Stephen M.*, Sasaki, Masahide
We investigate strategies for estimating a depolarizing channel for a finite dimensional system. Our analysis addresses the double optimization problem of selecting the best input probe state and the...
Optimal parameter estimation of a depolarizing channel (2002)
Ban, Masashi, Barnett, Stephen M., Sasaki, Masahide
We investigate strategies for estimating a depolarizing channel for a finite dimensional system. Our analysis addresses the double optimization problem of selecting the best input probe state and the...
Retrodiction of Generalised Measurement Outcomes (2002)
Chefles, Anthony, Sasaki, Masahide
If a generalised measurement is performed on a quantum system and we do not know the outcome, are we able to retrodict it with a second measurement? We obtain a necessary and sufficient condition for...
Optimal parameter estimation of depolarizing channel (2002)
Sasaki, Masahide, Ban, Masashi, Barnett, Stephen M.
We investigate strategies for estimating a depolarizing channel for a finite dimensional system. Our analysis addresses the double optimization problem of selecting the best input probe state and the...
Continuous variable teleportation as a generalized thermalizing quantum channel (2002)
Ban, Masashi, Sasaki, Masahide, Takeoka, Masahiro
A quantum channel is derived for continuous variable teleportation which is performed by means of an arbitrary entangled state and the standard protocol. When a Gaussian entangled state such as a...
Quantum learning and universal quantum matching machine (2002)
Sasaki, Masahide, Carlini, Alberto
Suppose that three kinds of quantum systems are given in some unknown states $\ket f^{\otimes N}$, $\ket{g_1}^{\otimes K}$, and $\ket{g_2}^{\otimes K}$, and we want to decide which \textit{template}...
Optimum detection for extracting maximum information from symmetric qubit sets (2001)
Mizuno, Jun, Fujiwara, Mikio, Akiba, Makoto, Kawanishi, Tetsuya, Barnett, Stephen M.*, Sasaki, Masahide
We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have...
Optimum detection for extracting maximum information from symmetric qubit sets (2001)
Mizuno, Jun, Fujiwara, Mikio, Akiba, Makoto, Kawanishi, Tetsuya, Barnett, Stephen M., Sasaki, Masahide
We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have...
Quantum channel of continuous variable teleportation and nonclassicality of quantum states (2001)
Takeoka, Masahiro, Ban, Masashi, Sasaki, Masahide
Noisy teleportation of nonclassical quantum states via a two-mode squeezed-vacuum state is studied with the completely positive map and the Glauber-Sudarshan $P$-function. Using the nonclassical...
Fidelity and the communication of quantum information (2001)
Barnett, Stephen M.*, Gilson, Claire R., Sasaki, Masahide
We compare and contrast the error probability and fidelity as measures of the quality of the receiver's measurement strategy for a quantum communications system. The error probability is a measure of...
Fidelity and the communication of quantum information (2001)
Barnett, Stephen M., Gilson, Claire R., Sasaki, Masahide
We compare and contrast the error probability and fidelity as measures of the quality of the receiver's measurement strategy for a quantum communications system. The error probability is a measure of...
Fidelity and the communication of quantum information (2001)
Barnett, Stephen M., Gilson, Claire R., Sasaki, Masahide
We compare and contrast the error probability and fidelity as measures of the quality of the receiver's measurement strategy for a quantum communications system. The error probability is a measure of...
Optimum detection for extracting maximum information from symmetric qubit sets (2001)
Mizuno, Jun, Fujiwara, Mikio, Akiba, Makoto, Kawanishi, Tetsuya, Barnett, Stephen M., Sasaki, Masahide
We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have...
Experimental realization of optimal detection strategies for overcomplete states (2001)
Clarke, Roger B.M., Kendon, Vivien M., Chefles, Anthony, Barnett, Stephen M.*, Riis, Erling*, Sasaki, Masahide
We present the results of generalized measurements of optical polarization designed to provide one of three or four distinct outcomes. This has allowed us to discriminate between nonorthogonal...
Experimental realization of optimal detection strategies for overcomplete states (2001)
Clarke, Roger B.M., Kendon, Vivien M., Chefles, Anthony, Barnett, Stephen M., Riis, Erling, Sasaki, Masahide
We present the results of generalized measurements of optical polarization designed to provide one of three or four distinct outcomes. This has allowed us to discriminate between nonorthogonal...
Entangled state based on nonorthogonal state (2001)
Hirota, Osamu, Sasaki, Masahide
Properties of entangled states based on nonorthogonal states are clarified. Especially, it is shown that they can have complete degree of entanglement.
Experimental realization of optimal detection strategies for overcomplete states (2000)
Clarke, Roger B. M., Kendon, Vivien M., Chefles, Anthony, Barnett, Stephen M., Riis, Erling, Sasaki, Masahide
We present the results of generalized measurements of optical polarization designed to provide one of three or four distinct outcomes. This has allowed us to discriminate between nonorthogonal...
Accessible information and optimal strategies for real symmetrical quantum sources (1999)
Sasaki, Masahide, Barnett, Stephen M.*, Jozsa, Richard, Osaki, Masao, Hirota, Osamu
We study the problem of optimizing the Shannon mutual information for sources of real quantum states, i.e., sources for which there is a basis in which all of the states have only real components. We...
Accessible information and optimal strategies for real symmetrical quantum sources (1999)
Sasaki, Masahide, Barnett, Stephen M., Jozsa, Richard, Osaki, Masao, Hirota, Osamu
We study the problem of optimizing the Shannon mutual information for sources of real quantum states, i.e., sources for which there is a basis in which all of the states have only real components. We...
Accessible information and optimal strategies for real symmetrical quantum sources (1998)
Sasaki, Masahide, Barnett, Stephen M., Jozsa, Richard, Osaki, Masao, Hirota, Osamu
We study the problem of optimizing the Shannon mutual information for sources of real quantum states i.e. sources for which there is a basis in which all the states have only real components. We...
Quantum channels showing superadditivity in capacity (1998)
Sasaki, Masahide, Kato, Kentaro, Izutsu, Masayuki, Hirota, Osamu
This was significantly extended from the previous article quant-ph/9705043,especially in an information theoretic aspect, by adding new results.
Realization of a collective decoding of codeword states (1998)
Sasaki, Masahide, Sasaki-Usuda, Tsuyoshi, Izutsu, Masayuki, Hirota, Osamu
This was also extended from the previous article quant-ph/9705043, especially in a realization of the decoding process.
A simple quantum channel having superadditivity of channel capacity (1997)
Sasaki, Masahide, Kato, Kentaro, Izutsu, Masayuki, Hirota, Osamu
When classical information is sent through a quantum channel of nonorthogonal states, there is a possibility that transmittable classical information exceeds a channel capacity in a single use of the...
Watanabe, Junichi, Sasaki, Masahide, Suzuki, Yutaka, Sugano, Sumio
FULL-malaria is a database for a full-length-enriched cDNA library from the human malaria parasite Plasmodium falciparum (http://133.11.149.55/). Because of its medical importance, this organism is...
Watanabe, Junichi, Suzuki, Yutaka, Sasaki, Masahide, Sugano, Sumio
Full-malaria (http://fullmal.ims.u-tokyo.ac.jp), a database for full-length cDNAs from the human malaria parasite, Plasmodium falciparum has been updated in at least three points. (i) We added 8934...
Fugu ESTs: New Resources for Transcription Analysis and Genome Annotation
Clark, Melody S., Edwards, Yvonne J.K., Peterson, Dan, Clifton, Sandra W., Thompson, Amanda J., Sasaki, Masahide, ...
The draft Fugu rubripes genome was released in 2002, at which time relatively few cDNAs were available to aid in the annotation of genes. The data presented here describe the sequencing and analysis...
Watanabe, Junichi, Sasaki, Masahide, Suzuki, Yutaka, Sugano, Sumio
FULL-malaria is a database for a full-length-enriched cDNA library from the human malaria parasite Plasmodium falciparum (http://133.11.149.55/). Because of its medical importance, this organism is...
Watanabe, Junichi, Suzuki, Yutaka, Sasaki, Masahide, Sugano, Sumio
Full-malaria (http://fullmal.ims.u-tokyo.ac.jp), a database for full-length cDNAs from the human malaria parasite, Plasmodium falciparum has been updated in at least three points. (i) We added 8934...
Fugu ESTs: New Resources for Transcription Analysis and Genome Annotation
Clark, Melody S., Edwards, Yvonne J.K., Peterson, Dan, Clifton, Sandra W., Thompson, Amanda J., Sasaki, Masahide, ...
The draft Fugu rubripes genome was released in 2002, at which time relatively few cDNAs were available to aid in the annotation of genes. The data presented here describe the sequencing and analysis...
Watanabe, Junichi, Wakaguri, Hiroyuki, Sasaki, Masahide, Suzuki, Yutaka, Sugano, Sumio
Comparasite is a database for comparative studies of transcriptomes of parasites. In this database, each data is defined by the full-length cDNAs from various apicomplexan parasites. It integrates...