US 12,461,305 B2
Quantum circuit, quantum computer, and method of manufacturing quantum circuit
Tetsuya Miyatake, Isehara (JP)
Assigned to Fujitsu Limited, Kawasaki (JP)
Filed by Fujitsu Limited, Kawasaki (JP)
Filed on Mar. 24, 2023, as Appl. No. 18/189,729.
Application 18/189,729 is a continuation of application No. PCT/JP2020/044622, filed on Dec. 1, 2020.
Prior Publication US 2023/0280528 A1, Sep. 7, 2023
Int. Cl. G02B 6/122 (2006.01); G02B 6/13 (2006.01)
CPC G02B 6/122 (2013.01) [G02B 6/13 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method of manufacturing a quantum circuit, the method comprising:
forming, in a diamond layer that includes a color center, an optical waveguide optically coupled the color center, the diamond layer having a first principal surface and a second principal surface,
wherein the optical waveguide includes:
a core region that includes the color center; and
an optical confinement region provided around the core region,
a refractive index of the optical confinement region is lower than the refractive index of the core region, and
the forming the optical waveguide includes:
forming, in the diamond layer, a groove that is away from the color center and has an inclined surface;
forming a reflective film over the inclined surface;
forming a first region on a side of the first principal surface of the color center by emitting femtosecond laser light to a first part of the reflective film and concentrating the femtosecond laser light reflected by the reflective film onto the side of the first principal surface of the color center to lower the refractive index of the first part of the diamond layer;
forming a second region on a side of the second principal surface of the color center by emitting the femtosecond laser light to a second part of the reflective film and concentrating the femtosecond laser light reflected by the reflective film onto the side of the second principal surface of the color center to lower the refractive index of the second part of the diamond layer;
forming a third region on a first side of the core region by emitting the femtosecond laser light to the first part of the first principal surface and concentrating the femtosecond laser light onto the first side of the core region in a first direction parallel to the first principal surface to lower the refractive index of the second part of the diamond layer; and
forming a fourth region on a second side of the core region by emitting the femtosecond laser light to the second part of the first principal surface and concentrating the femtosecond laser light onto the second side of the core region in the first direction to lower the refractive index of the second part of the diamond layer.