Fujitsu Corporation

The University of Tokyo

Kazuya Takemoto

Tatsuya Usuki

Motomu Takatsu

Satoshi Matsubara

Yasuhiko Arakawa

Sanroku Tsukamoto

Takayuki Shibasaki

Noboru Yoneoka

Jumpei Koyama

Akihiko Ohwada

Toshiyuki Miyazawa

A problem is inputted into an operation unit. A computation unit searches for a ground state of an Ising model. A management unit converts the problem inputted from the operation unit to the Ising model, inputs the Ising model produced by conversion and initial operating conditions into the computation unit, and has the computation unit search for the ground state using overall operating conditions produced by changing the initial operating conditions based on a result of the computation unit searching for the ground state using the initial operating conditions.

Optimization apparatus and control method for optimization apparatus using ising models

A light collecting device is disclosed that is able to couple light from a light emission structure to an optical fiber at low loss. The light collecting device includes an excitation light source for emitting excitation light to an optical fiber; a light condensing optical system which condenses the excitation light from the optical fiber to a light emission structure, and directs light reflected in the light emission structure and light generated in the light emission structure back to the optical fiber; a reflecting light detector for detecting intensity of the reflected light; a first optical divider for dividing the emission light and the reflected light based on their wavelengths, directing the emission light to the optical fiber, and propagating the reflected light to the excitation light source; a second optical divider arranged close to the excitation light source for propagating the excitation light to the first optical divider, and propagating the reflected light to the reflecting light detector; a position controller for controlling a light condensing position of the excitation light to be irradiated to the light emission structure; a unit for scanning the light condensing position of the excitation light, and acquiring a relationship of intensity of the reflected light and the light condensing position of the excitation light; and a unit for optimizing the light condensing position based on the intensity of the reflected light and the light condensing position of the excitation light.

Light collecting device and single-photon generation device

A private key delivery system and a private key delivery method are disclosed. The private key delivery system includes a transmitter, a receiver, and an optical transmission line connecting the transmitter and the receiver. The transmitter includes a single photon generating unit for simultaneously generating two or more single photons having different wavelengths using a quantum dot structure that has quantum dots of various sizes, an optical splitter for splitting the single photons by wavelengths, a phase modulating unit for modulating each of the single photons split by the wavelengths with private key information, and an optical multiplexer for multiplexing the modulated single photons of the different wavelength and for transmitting the multiplexed single photons to the optical transmission line. The multiplexed single photons are received by the receiver, and the private key information is taken out from the received single photons.

Private key delivery system and a private key delivery method

A single-photon generator includes a single-photon generating device generating a single-photon pulse having a wavelength on the shorter wavelength side than a communication wavelength band, and a single-photon wavelength conversion device performing wavelength conversion of the single-photon pulse into a single-photon pulse of the communication wavelength band, using pump pulse light for single-photon wavelength conversion.

Single-photon generator

A single-photon generator includes an exciton generation part including therein a quantum dot, an excitation part for generating an exciton in the exciton generator part, a recombination control part for controlling recombination timing of the exciton in the exciton generation part, and an optical window provided in the exciton generation part so as to pass a single photon formed as a result of recombination of the exciton, wherein the recombination control part causes, in the exciton generation part, recombination of the excitons at longer intervals than a recombination lifetime of a exciton molecule.

Growing community of inventors

Kawasaki, Japan

Kazuya Takemoto