National Institute of Information and Communications Technology, Incorporated

Nec Corporation

National Institute of Information and Communications Technology, Incorporated Administrative Agency

Hokkaido University

The University of Tokyo

University of Strathclyde

National Institutes of Natural Sciences

University of Hertfordshire

Masahide Sasaki

Mikio Fujiwara

Makoto Akiba

Akihisa Tomita

Ken-ichiro Yoshino

Masahiro Takeoka

Atsushi Hasegawa

Hiroyuki Endo

Hiroshi Matsuo

Yoshihiro Nambu

Morio Toyoshima

Stephen Mark Barnett

Masato Koashi

Masao Nagasaki

Yasuyoshi Mitsumori

John A Vaccaro

Erika Andersson

Hirohisa Nagata

An object is to prevent eavesdropping in quantum key distribution. A photon detector outputs an output current indicating a result of detecting a quantum signal. A current-voltage conversion unit converts the output current into an output voltage signal. An analog-to-digital converter outputs an output voltage signal obtained by analog-digital conversion of the output voltage signal. A signal processing unit performs predetermined signal processing on the output voltage signal, and outputs a photon detection signal indicating a result of detecting the quantum signal. When a time difference between a timing at which the quantum signal is incident into the photon detector and a reference timing determined based on a clock signal is not within a determination range, the photon detection signal is not output from the signal processing unit.

Photon detection device, reception device, quantum key distribution system, and method for detecting quantum signal

A personal information protection management system for genomic data includes data storage, role storage, a filter, and a data output part. The data storage is configured to store genomic data. The role storage is configured to store an identifier of a data output destination and a role in association with each other, the role including a detail of filtering for removing from genomic data a part that is not to be outputted. The filter is configured to filter the stored genomic data based on the stored role. The data output part is configured to output the filtered genomic data to the data output destination. The filter is configured to obtain a data request signal transmitted from the data output destination and, based on the role that is associated with the identifier included in the obtained data request signal, filter the genomic data.

Personal information protection management system for genomic data

An encryption key generating device includes a shared key separator separating a shared key into a first key and a second key and storing the first key in a non-volatile memory and storing the second key in a volatile memory; a key extender extending the second key to the same key length as that of the first key and storing the second key extended as a third key in the volatile memory; a key calculator calculating an encryption key by an exclusive-OR of the first key and the third key and storing it in the volatile memory.

Encryption key generating device, encryption key generating program, and encryption key generating/erasing method

A secret key sharing system includes a transceiver in a first layer, a plurality of transceivers in a second layer, and a plurality of transceivers in a third layer. The transceivers in the second layer receive a first random number from the transceiver in the first layer via a directional carrier wave. The transceivers in the third layer receive a second random number from one of the transceivers in the second layer via the carrier wave. The transceiver in the first layer and the transceivers in the second layer share a first secret key based on the first random number, and the one of the transceivers in the second layer and the plurality of transceivers in the third layer share a second secret key based on the second random number.

Secret key sharing system and secret key sharing method

A quantum key distribution device is provided with an encoding unit which encodes an optical pulse train; an intensity modulating unit which subjects the encoded optical pulse train to N (where N is an integer at least equal to 3) types of intensity modulation having mutually different intensities, with different timings; and a first key distillation processing unit which generates an encryption key on the basis of a data sequence obtained by removing data obtained from an optical pulse having a specific modulation pattern from a data sequence used by the encoding unit and the intensity modulating unit.

Transmitting device, receiving device, quantum key distribution method, and quantum key distribution program for quantum key distribution system

Provided is a communication system in which a terminal communicates with a server via a portable communication network used for communication between smartphones. The smart phone includes first pre-shared key and encryption keys, the terminal includes a second pre-shared key, the server includes the encryption keys same as the encryption keys included in the smartphone, authentication between the terminal and the smartphone is performed by using the first pre-shared key and the second pre-shared key, and the terminal and the server perform communication via the smartphone by performing key synchronization of the encryption keys while setting a hash value of the encryption keys as an ID.

Communication system

It is an object of the present invention to provide a network system for quantum key distribution (QKD) for free space and fiber networks. The system of the present invention generates a couple of photons which have different wavelength and inputs each of the photons into the asymmetric Mach-Zehnder interferometer to obtain time-bin entangled state. It provides polarization information with one part of the photons. Then it can obtain hybrid quantum entanglement. The system of the present invention may be used hybrid quantum key distribution system applied for both free space and fibers.

Time-bin polarization format exchange technique for entangled optical source

A method for reducing low frequency noise of a transistor operable at cryogenic temperatures includes a first step in which the transistor is illuminated with a light in a state that the transistor is activated and flowed current by supplying a power at a predetermined temperature, and a second step in which the transistor is operated at the predetermined temperature after the illumination of the light.

Method for reducing low frequency noise of transistor

Quantum source coding apparatus for communication of quantum information comprising: a quantum state preparation device for converting input messages into block messages; a coding device for producing coded signals by compressing the block messages prepared by the quantum state preparation device; and an output device for outputting the coded signals produced by the coding device.

Quantum source coding apparatus and quantum information communication system

This invention provides a method for manufacturing a circuit for photon number counting without destroying a FET within the circuit by manufacturing a photodetector for weak light, the photodetector for weak light comprising a circuit on a substrate, the circuit comprising light detection means and a field effect transistor (FET), the method comprising: a light detection means connection step; an FET electrode-to-substrate electrode connection step; an external electrode connection step, a light detection means-to-gate connection step.

Method for manufacturing photodetector for weak light

The present invention provides a photodetector for weak light that can prevent noise from impurities, prevent electrodes from disconnecting from the substrate, and can be easily cooled; the present invention further provides a photodetector for weak light that can count the number of photons; the present invention solves the above problems by using an ultraviolet light transparent substrate on the photodetector for weak light.

Photodetector for weak light with UV transparent substrates

This invention provides a photodetector for weak light and a weak light detection system including the photodetector for weak light the photodetector for weak light is comprised of a substrate on which an integrating read circuit including a PIN photodiode or an APD and an FET is mounted, wherein the entire assembly is mounted while separating the substrate from a ground potential without grounding the substrate, such a photodetector for weak light can reduce noise and ensure a high enough sensitivity enough to be able to discriminate the number of photons.

Photo detector for weak light

The present invention provides a photodetector for weak light that can release charge from the circuit without increasing capacity; the present invention being characterized by a photodetector for weak light that has a charge release means which permits the photodetector for weak light of the present invention to avoid increasing its capacity because it does not require a reset transistor integrated with the photodector, rather the charge reset means of the present invention lowers mounting capacity by removing itself from the circuit after it releases the charge.

Growing community of inventors

Koganei, Japan

Masahide Sasaki