Quantum computer and quantum computing using ising model

Patent metadata

Field	Value
Publication number	US-9342792-B2
Application number	US-201314074295-A
Country	US
Kind code	B2
Filing date	Nov 7, 2013
Priority date	Jan 11, 2013
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

For each pair of a plurality of slave lasers B for which injection synchronization is performed by a master laser M, by controlling the intensity of light exchanged between two slave lasers B and an optical path length between the two slave lasers B using a slave-to-laser intensity control unit IA and an inter-slave laser optical path length control unit IP, the magnitude and the sign of pseudo ising interaction J ij between the two slave lasers B are implemented. After the plurality of slave lasers B arrive at a steady state, by measuring relative values of the oscillation phases of the plurality of slave lasers B with respect to the oscillation phase of the master laser M by using an oscillation phase measuring unit PM, pseudo ising spins σ i of the plurality of slave lasers B are measured.

First claim

What is claimed is:

1. A quantum computer using an ising model comprising:
a plurality of coherent oscillators that oscillate light having polarization polarized in a same direction determined in advance in correspondence with a plurality of sites of the ising model;
a master oscillator that performs injection synchronization for the plurality of coherent oscillators and oscillates the light having polarization polarized in the same direction determined in advance;
a master oscillator-to-coherent oscillator optical path unit that is arranged between the master oscillator and each one of the coherent oscillators;
an inter-coherent oscillator optical path unit that is arranged between two coherent oscillators for each pair of the plurality of the coherent oscillators;
an oscillation frequency control unit that is arranged in each master oscillator-to-coherent oscillator optical path unit and controls an oscillation frequency of each one of the coherent oscillators so as to be an oscillation frequency of the master oscillator;
an inter-coherent oscillator intensity control unit that is arranged in each inter-coherent oscillator optical path unit for each pair of the plurality of the coherent oscillators and implements a magnitude of pseudo ising interaction between two coherent oscillators by controlling an intensity of light exchanged between the two coherent oscillators;
an inter-coherent oscillator optical path length control unit that is arranged in each inter-coherent oscillator optical path unit for each pair of the plurality of the coherent oscillators and implements a sign of the pseudo ising interaction between two coherent oscillators by controlling an optical path length between the two coherent oscillators; and
an oscillation phase measuring unit that measures pseudo ising spins of the plurality of the coherent oscillators by measuring relative values of oscillation phases of the plurality of the coherent oscillators with respect to the oscillation phase of the master oscillator after the plurality of the coherent oscillators arrive at a steady state.

2. The quantum computer using an ising model according to claim 1 , wherein each inter-coherent oscillator optical path length control unit implements the sign of pseudo ising interaction between two coherent oscillators by performing control such that an optical path length between the two coherent oscillators is a half-integer multiple or an integer multiple of an oscillation wavelength of the injection synchronization.

3. The quantum computer using an ising model according to claim 1 , wherein the oscillation phase measuring unit determines that directions of pseudo ising spins of two coherent oscillators to be the same when oscillation phases of both the coherent oscillators lead before or lag behind the oscillation phase of the master oscillator for each pair of the plurality of the coherent oscillators and determines that the directions of the pseudo ising spins of two coherent oscillators to be different from each other when an oscillation phase of one coherent oscillator leads before the oscillation phase of the master oscillator and the oscillation phase of the other coherent oscillator lags behind the oscillation phase of the master oscillator for each pair of the plurality of the coherent oscillators.

4. The quantum computer using an ising model according to claim 1 , further comprising:
a master oscillator-to-coherent oscillator intensity control unit that is arranged in each master oscillator-to-coherent oscillator optical path unit and implements the magnitude of pseudo Zeeman energy in each coherent oscillator by controlling the intensity of light injected into each coherent oscillator; and
a master oscillator-to-coherent oscillator phase control unit that is arranged in each master oscillator-to-coherent oscillator optical path unit and implements the sign of the pseudo Zeeman energy in each coherent oscillator by controlling the phase of light injected into each coherent oscillator.

5. The quantum computer using an ising model according to claim 4 , wherein each master oscillator-to-coherent oscillator phase control unit implements the sign of the pseudo Zeeman energy in each coherent oscillator by controlling lead or lag of an injection phase for each coherent oscillator with respect to the oscillation phase of the master oscillator.

6. The quantum computer using an ising model according to claim 1 , wherein each oscillation frequency control unit controls the oscillation frequency of each coherent oscillator so as to be the oscillation frequency of the master oscillator by performing control such that an interference intensity of oscillated light of each coherent oscillator and oscillated light of the master oscillator is an extreme value with respect to a change in the oscillation frequency of each coherent oscillator.

7. The quantum computer using an ising model according to claim 1 , wherein each inter-coherent oscillator optical path length control unit controls an optical path length between two coherent oscillators so as to be a half-integer multiple or an integer multiple of an oscillation wavelength of the injection synchronization by performing control such that an interference intensity of oscillated light of the two coherent oscillators is an extreme value with respect to a change in the optical path length between the two coherent oscillators.

8. The quantum computer using an ising model according to claim 1 , wherein control of the oscillation frequency of each coherent oscillator in each oscillation frequency control unit, control of the optical path length between two coherent oscillators in each inter-coherent oscillator optical path length control unit, and measurement of the pseudo ising spins of the plurality of the coherent oscillators in the oscillation phase measuring unit are performed in the mentioned order.

9. The quantum computer using an ising model according to claim 1 , further comprising a pumping current control unit that performs gradual increase control of pumping currents of two coherent oscillators for the two coherent oscillators performing pseudo ising interaction through each inter-coherent oscillator optical path unit in a state in which the magnitude and the sign of the pseudo ising intersection between the two coherent oscillators are implemented to be fixed values and performs fixing control of the pumping currents of the two coherent oscillators at a time point when the plurality of the coherent oscillators arrive at one integrally oscillation mode for the first time,
wherein the oscillation phase measuring unit, after the plurality of the coherent oscillators arrive at one integrally oscillation mode so as to arrive at a steady state, measures the pseudo ising spins of the plurality of the coherent oscillators by measuring relative values of the oscillation phases of the plurality of the coherent oscillators with respect to the oscillation phase of the master oscillator.

10. The quantum computer using an ising model according to claim 1 , further comprising an adjacent ising spin direction fixing unit that is arranged in each master oscillator-to-coherent oscillator optical path unit, and, for two coherent oscillators performing pseudo ising interaction through each inter-coherent oscillator optical path unit, by controlling the intensity and the phase of light injected into the two coherent oscillators when relative values of the oscillation phases of the two coherent oscillators with respect to the oscillation phase of the master oscillator are not measured to be meaningful, fixes the directions of pseudo ising spins of the two coherent oscillators to be different from each other when the sign of the pseu

Assignees

• Kek High Energy Accelerator
• Univ Leland Stanford Junior

Inventors

• Utsunomiya Shoko
• Takata Kenta
• Yamamoto Yoshihisa
• Wen Kai

Classifications

• G01J9/00 Primary

  Measuring optical phase difference (devices or arrangements for controlling the phase of light beams G02F1/01); Determining degree of coherence; Measuring optical wavelength (spectrometry G01J3/00) · CPC title

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title

• G06N99/002 Primary

  Physics · mapped topic