QUANTUM COMPUTER AND QUANTUM COMPUTING METHOD

• US 20170059964A1
• Filed: 06/09/2016
• Published: 03/02/2017
• Est. Priority Date: 06/11/2015
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: NAKAMURA, Satoshi, ICHIMURA, Kouichi, GOTO, Hayato, KUJIRAOKA, Mamiko
• Granted Patent: US 10,365,538 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: G02F 3/00 Optical logic elements; Optical bistable devices
• CPC Class Codes: G06N 10/00 Quantum computing, i.e. information processing based on quantum-mechanical phenomena
• CPC Class Codes: Y10S 977/933 Spintronics or quantum computing

Abstract

According to an embodiment, a quantum computer includes first physical systems provided in a cavity, a second physical system provided in the cavity, and a light source unit. The first physical systems include a transition coupled to a common cavity mode of the cavity. The second physical system includes a first transition coupled to the common cavity mode and a second transition. The light source unit generates a first and a second light beam to manipulate two of the first physical systems and generates a third light beam that resonates with the second transition. The third light beam is radiated to the second physical system during a period when the first and the second light beam are simultaneously radiated to the two first physical systems.

Claims

1. A quantum computer comprising:

a plurality of first physical systems provided in a cavity, the plurality of first physical systems having three or more energy levels including two energy levels used for a qubit, the plurality of first physical systems including a transition coupled to a common cavity mode of the cavity;

a second physical system provided in the cavity, the second physical system having three or more energy levels, the second physical system including a first transition coupled to the common cavity mode and a second transition different from the first transition;

a light source unit configured to generate a first laser light beam and a second laser light beam to manipulate two of the plurality of first physical systems, the light source unit being further configured to generate a third laser light beam that resonates with the second transition, and

wherein the third laser light beam is radiated to the second physical system during a period when the first laser light beam and the second laser light beam are simultaneously radiated to the two first physical systems.

2. The quantum computer according to claim 1, wherein the first laser light beam, the second laser light beam, and the third laser light beam are controlled to perform a quantum gate such that Ω

_e≧

Ω

₁/2 and Ω

_e≧

2 Ω

₂/2 are satisfied, where Ω

₁ denotes a Rabi frequency between the first laser light beam and a transition resonating with the first laser light beam, Ω

₂ denotes a Rabi frequency between the second laser light beam and a transition resonating with the second laser light beam, and Ω

_e denotes a Rabi frequency between the third laser light beam and a transition resonating with the third laser light beam.

3. The quantum computer according to claim 2, wherein the third laser light beam is controlled to perform the quantum gate such that Ω

_e≧

√

{square root over (Ω

₁²+Ω

₂²)} is satisfied.

4. The quantum computer according to claim 3, wherein the third laser light beam is controlled to perform the quantum gate such that Ω

_e≦

2√

{square root over (Ω

₁₀²+Ω

₂₀²)} is satisfied, where Ω

₁₀ denotes a maximum value of the Rabi frequency Ω

₁ in performing the quantum gate, and Ω

₂₀ denotes a maximum value of the Rabi frequency Ω

₂ in performing the quantum gate.

5. The quantum computer according to claim 1, wherein the third laser light beam is controlled to perform a quantum gate such that g_e≦

Ω

_e is satisfied, where Ω

_e denotes a Rabi frequency between the third laser light beam and a transition resonating with the third laser light beam and g_e denotes a coupling constant between the second physical system and the cavity mode.

6. The quantum computer according to claim 1, comprising a plurality of the second physical systems, wherein a difference in resonant frequency between the plurality of first physical systems is larger than a Rabi frequency between the first laser light beam and a transition resonating with the first laser light beam and a Rabi frequency between the second laser light beam and a transition resonating with the second laser light beam, and a difference in resonant frequency between the plurality of second physical systems is smaller than a Rabi frequency between the third laser light beam and a transition resonating with the third laser light beam.

7. A quantum computing method for a quantum computer comprising a plurality of first physical systems provided in a cavity, the plurality of first physical systems having three or more energy levels including two energy levels used for a qubit, the plurality of first physical systems including a transition coupled to a common cavity mode of the cavity, the quantum computer further comprising a second physical system provided in the cavity, the second physical system having three or more levels, the second physical system including a first transition coupled to the common cavity mode and a second transition different from the first transition, the method comprising:

generating a first laser light beam and a second laser light beam to manipulate two of the plurality of first physical systems;

generating a third laser light beam that resonates with the second transition; and

radiating the third laser light beam to the second physical system during a period when the first laser light beam and the second laser light beam are simultaneously radiated to the two first physical systems.