US-20260126590-A1 - QUANTUM DEVICE AND METHOD FOR MANUFACTURING QUANTUM DEVICE

US20260126590A1US 20260126590 A1US20260126590 A1US 20260126590A1US-20260126590-A1

Abstract

A quantum device includes a first waveguide, an optical resonator that is coupled to the first waveguide, a first light source that introduces first light into the first waveguide, and a second light source that irradiates the optical resonator with second light. The optical resonator includes a second waveguide extending in a first direction and a color center provided in the second waveguide. The second light source has an optical axis in a second direction perpendicular to the first direction, and the color center is irradiated with the second light.

Inventors

Tetsuro ISHIGURO
Tetsuya Miyatake
Toshiki IWAI
Kenichi Kawaguchi
Yoshiyasu Doi
Shintaro Sato

Assignees

FUJITSU LIMITED

Dates

Publication Date: 20260507
Application Date: 20241118

Claims (15)

1 . A quantum device comprising: a first waveguide; an optical resonator that is coupled to the first waveguide; a first light source that introduces first light into the first waveguide; and a second light source that irradiates the optical resonator with second light, wherein the optical resonator includes a second waveguide that extends in a first direction and a color center that is provided in the second waveguide, the second light source has an optical axis in a second direction perpendicular to the first direction, and the color center is irradiated with the second light.
2 . The quantum device according to claim 1 , wherein third light of which wavelength is different from that of the first light is output from the optical resonator to the first waveguide.
3 . The quantum device according to claim 1 , wherein the color center is provided at one end portion of the second waveguide, and the first waveguide is coupled to the other end portion of the second waveguide.
4 . The quantum device according to claim 1 , wherein the device includes a static magnetic field source that generates a magnetic field that reaches the color center, and a microwave source that generates a microwave that reaches the color center.
5 . The quantum device according to claim 1 , wherein the color center includes a composite defect of N, Si, Ge, Sn, or Pb, or arbitrary combination thereof, and a vacancy.
6 . The quantum device according to claim 1 , wherein material of the second waveguide is diamond, and a refractive index of material of the first waveguide is lower than a refractive index of diamond.
7 . The quantum device according to claim 1 , wherein the first light source is a quantum light source, and the second light source is a coherent light source.
8 . The quantum device according to claim 1 , wherein a plurality of openings arranged in the first direction is formed at equal intervals in the second waveguide.
9 . The quantum device according to claim 1 , wherein a coupling coefficient of the optical resonator is smaller than an absolute value of a difference between a resonance frequency of the optical resonator and a light emission frequency of the color center.
10 . The quantum device according to claim 1 , wherein the first light source is a coherent light source, and when a light intensity of the second light source is Ωd, a coupling coefficient of the optical resonator is g, a resonance frequency of the optical resonator is ω c , and a light emission frequency of the color center is ω a , χ = g 2 / ( ω c - ω a ) ⁢ and cos 2 ( tan - 1 ( 2 ⁢ Ω d / χ ) ) = sin 2 ( tan - 1 ( 2 ⁢ Ω d / χ ) ) are satisfied.
11 . The quantum device according to claim 10 , wherein a frequency of the second light is equal to ω a −2χ.
12 . The quantum device according to claim 1 , wherein the device includes a support that supports the first waveguide and the optical resonator.
13 . The quantum device according to claim 12 , wherein a refractive index of material of the support is lower than a refractive index of diamond.
14 . A method for manufacturing a quantum device comprising: a step of providing an optical resonator that is coupled to a first waveguide; a step of providing a first light source that introduces first light into the first waveguide; and a step of providing a second light source that irradiates the optical resonator with second light, wherein the optical resonator includes a second waveguide that extends in a first direction and a color center that is provided in the second waveguide, and the second light source has an optical axis in a second direction perpendicular to the first direction, and is disposed such that the color center is irradiated with the second light.
15 . A quantum computation apparatus comprising a quantum device, the quantum device including: a first waveguide; an optical resonator that is coupled to the first waveguide; a first light source that introduces first light into the first waveguide; and a second light source that irradiates the optical resonator with second light, wherein the optical resonator includes a second waveguide that extends in a first direction and a color center that is provided in the second waveguide, the second light source has an optical axis in a second direction perpendicular to the first direction, and the color center is irradiated with the second light.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation application of International Application PCT/JP2022/021961 filed on May 30, 2022 and designated the U.S., the entire contents of which are incorporated herein by reference. FIELD The embodiments discussed herein are related to a quantum device and a method for manufacturing a quantum device. BACKGROUND In recent years, research and development of quantum computers have been vigorously advanced. For example, a quantum computer that uses a level of an electron spin of a color center of diamond as a qubit is known. In such quantum computer, information of electron spin is converted into information of photon, and optical reading is performed. Example of the related art include: [PTL 1] Japanese Laid-open Patent Publication No. 2014-216596; [PTL 2] International Publication Pamphlet No. WO 2020/203746; and [NPL 1] Kazuki Koshino and three others, “Deterministic Quantum State Switching by Single Photon”, Journal of the Physical Society of Japan, Vol. 1, No. 1, 2014. SUMMARY According to an aspect of the embodiments, there is provided a quantum device including: a first waveguide; an optical resonator that is coupled to the first waveguide; a first light source that introduces first light into the first waveguide; and a second light source that irradiates the optical resonator with second light, wherein the optical resonator includes a second waveguide that extends in a first direction and a color center that is provided in the second waveguide, the second light source has an optical axis in a second direction perpendicular to the first direction, and the color center is irradiated with the second light. The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view illustrating a quantum device according to a first embodiment. FIG. 2 is a cross-sectional view illustrating the quantum device according to the first embodiment. FIG. 3 is a diagram illustrating an example of the operation of the quantum device according to the first embodiment. FIG. 4 is a diagram illustrating another example of the operation of the quantum device according to the first embodiment. FIG. 5 is a diagram illustrating a relationship between parameter (Ωd/χ) and γmn/γ (m is 3 or 4, and n is 1 or 2). FIG. 6 is a perspective view illustrating a method for manufacturing an optical resonator in the quantum device according to the first embodiment (part 1). FIG. 7 is a perspective view illustrating the method for manufacturing an optical resonator in the quantum device according to the first embodiment (part 2). FIG. 8 is a perspective view illustrating the method for manufacturing an optical resonator in the quantum device according to the first embodiment (part 3). FIG. 9 is a perspective view illustrating the method for manufacturing an optical resonator in the quantum device according to the first embodiment (part 4). FIG. 10 is a perspective view illustrating the method for manufacturing an optical resonator in the quantum device according to the first embodiment (part 5). FIG. 11 is a diagram illustrating a calculation result of electromagnetic field distribution related to the first embodiment. FIG. 12 is a diagram illustrating an intensity profile of a standing wave extracted in the vicinity of a color center. FIG. 13 is a plan view illustrating a quantum device according to a second embodiment. FIG. 14 is a plan view illustrating a quantum device according to a third embodiment. FIG. 15 is a diagram illustrating a quantum computation apparatus according to a fourth embodiment. DESCRIPTION OF EMBODIMENTS Optical transition used for reading a state occurs probabilistically based on the selection rule of quantum mechanics. Consequently, it is difficult for a conventional quantum device used in a quantum computer to convert information of electron spin into information of photon with high efficiency. An object of the present disclosure is to provide a quantum device capable of improving conversion efficiency of information of electron spin into information of photon, and a method for manufacturing a quantum device. Hereinafter, embodiments of the present disclosure will be specifically described with reference to the attached drawings. Note that, in the present specification and drawings, redundant description may be omitted by giving the same reference sign for constituent elements having substantially the same functional configuration. In the present disclosure, an X1-X2 direction, a Y1-Y2 direction, and a Z1-Z2 direction are directions orthogonal to one another. A plane including the X1-X2 direction and the Y1-Y2 direction is described as an XY p