Nippon Telegraph and Telephone Corporation

Inter-university Research Institute Corporation Research Organization of Information and Systems

Leland Stanford Junior University

Osaka University

Ntt Corporation

Hiroki Takesue

Toshimori Honjo

Takahiro Inagaki

Kensuke Inaba

Yoshihisa Yamamoto

Shoko Utsunomiya

Shuhei Tamate

Takuya Ikuta

Edo Waks

Kyo Inoue

Yoshitaka Haribara

Koji Igarashi

Eleni Diamanti

A calculation device of the present disclosure is characterized by implementing an item, which expresses a magnetic field, at each site by adding, to the conventional coherent Ising machine, a function for simulating the magnetic field item. Specifically, light having the amplitude of a predetermined sign is input in the conventional coherent Ising machine by dislocating an operation point of the push-pull-type optical modulator. When the operation point is dislocated to a + direction, DOPO (Degenerate Optical Parametric Oscillator) having the same wavelength as that of DOPO of an optical resonator and having a fixed initial phase difference from pump light into which the light is injected considerably tends to oscillate at 0 phase, and becomes reversed when the operation point is dislocated to a minus direction.

Computing device of Ising model

To provide a spiking neuron apparatus able to efficiently implement a simulation of a spiking neuron. A spiking neuron apparatus using a coherent Ising machine, the coherent Ising machine including: a resonator unit for amplifying a plurality of optical pulses; a measurement unit for measuring phases and amplitudes of the optical pulses to obtain a measurement result; and a feedback configuration for computing and feeding back an interaction related to a certain optical pulse using a coupling coefficient of Ising Model on the basis of the measurement result, the feedback configuration feedback inputting correlation determined by two coupling coefficients with opposite signs to two predetermined optical pulses of the optical pulses, the spiking neuron apparatus simulating a state of a spiking neuron using one of values of two optical pulses finally obtained by the measurement unit.

Spiking neuron device and combinatorial optimization problem calculation device

The present invention provides an optical phase synchronization method characterized by involving applying a small phase modulation signal (dither signal) to local oscillator light, acquiring an error signal that is dependent on a phase shift, and controlling the phase shift. The present invention further provides an optical phase synchronization method characterized by involving inducing a specific phase pattern in dummy pulses in an optical resonator using injection light, applying phase modulation to the local oscillator light, and thereby acquiring a part of the measurement result of the dummy pulses as the error signal. The present invention is further characterized by arranging calculation pulses and phase synchronization dummy pulses in a distributed manner (for example, alternately) and increasing a pulse width using a narrow band electrical filter.

Phase synchronization method and phase synchronization device

A Potts model computing device capable of computing a Potts problem that is a multivalued spin problem are described herein. The Potts model computing device includes: an Ising model computing device; a computation result storage and determination unit configured to store a value of a spin of the Ising model obtained in a case where a coupling coefficient is set in the Ising model computing device and to determine whether a computation is finished; and a coupling coefficient overwriting unit configured to update a coupling coefficient generated based on the stored value of the spin to the Ising model computing device. According to a value of a set of spins obtained as a computation result corresponding to a coupling coefficient set for an m-th time in the Ising model computing device, the coupling coefficient overwriting unit generates again a coupling coefficient to be set for an (m+1)-th iterative computation.

Potts model calculation device

The Ising model calculation device selects a solution having a consistent quality from among solutions obtained through the calculations with the evaluation index of a calculation accuracy. A coupling coefficient obtained by combining the Ising model coupling coefficient corresponding to a problem for which a solution should be calculated with the Ising model coupling coefficient corresponding to the check problem is set as a coupling coefficient used to calculate the interaction. With regard to a calculation value corresponding to the check spin among the calculation values using a plurality of light pulses, the compatibility as the solution of the check problem is judged. When the judgement result shows the compatibility as the solution of the check problem, a calculation value other than the calculation values corresponding to the check spin among the resultant calculation values is outputted as a solution to the problem for which a solution should be calculated.

Ising model calculation device

In an Ising spin measuring step, measurement is suspended after one set of measurement of all Ising spins {&#x3c3;} is completed before another set of measurement of all Ising spins {&#x3c3;} is restarted. In an Ising interaction computing step, all Ising interactions relating to all the Ising spins &#x3c3;can be computed with a sufficient time margin on the basis of most recent measurement of Ising spins &#x3c3;, after one set of measurement of all the Ising spins {&#x3c3;} is completed before another set of measurement of all the Ising spins {&#x3c3;} is restarted by the Ising spin measuring step.

Ising model quantum computation device

A parametric oscillator oscillates a plurality of pseudo spin pulses SPi having mutually an identical oscillation frequency by using parametric oscillation, an interaction implementing unit performs feedback implementation of a magnitude and a sign of interaction related to each pseudo spin pulse SPi (the proportionality coefficient &#x3bb;+&#x3a3;J&#x3c3;+&#x3a3;K&#x3c3;&#x3c3;with respect to &#x3c3;) by using a tentative measurement result of oscillation phases &#x3d5;(tentative) of the plurality of pseudo spin pulses SPi, and a pseudo spin measuring unit measures the pseudo spins &#x3c3;of the plurality of pseudo spin pulses SPi, based on a final measurement result of oscillation phases &#x3d5;(steady) of the plurality of pseudo spin pulses SPi.

Quantum computing device for Ising model, quantum parallel computing device for Ising model, and quantum computing method for Ising model

Differential phase shift (DPS) quantum key distribution (QKD) is provided, where the average number of photons per transmitted pulse is predetermined such that the secure key generation rate is maximal or nearly maximal, given other system parameters. These parameters include detector quantum efficiency, channel transmittance and pulse spacing (or clock rate). Additional system parameters that can optionally be included in the optimization include baseline error rate, sifted key error rate, detector dead time, detector dark count rate, and error correction algorithm performance factor. The security analysis leading to these results is based on consideration of a hybrid beam splitter and intercept-resend attack.

Growing community of inventors

Atsugi, Japan

Hiroki Takesue