Integrated microwave-to-optical single-photon transducer with strain-induced electro-optic material
Transducers and methods of making the same include a substrate having a cavity with a diameter that supports whispering gallery modes at a frequency of an input signal. A focusing structure in the cavity focuses the electric field of the input signal. A resonator directly under the focusing structure has a crystalline structure that generates an electro-optic effect when exposed to electrical fields. An electric field of the input signal modulates an output signal in the resonator via the electro-optic effect.
1. A quantum computing device, comprising:
a qubit configured to provide a first signal at a first frequency;
a transducer coupled to the qubit, comprising:
a substrate having a cylindrical cavity with a diameter that supports whispering gallery modes at the first frequency;
a central pin in the cavity; and
a resonator directly under the central pin, having a crystalline structure that generates an electro-optic effect when exposed to electrical fields, wherein an electric field of the input signal modulates a second signal at a second frequency in the resonator via the electro-optic effect; and
a waveguide, optically coupled to the resonator, that is configured to convey the modulated second signal away from the resonator.
2. The quantum computing device of claim 1 , wherein the transducer further comprises a superconducting film that is formed directly on an inner surface of the cavity and on an outer surface of the central pin.
3. The quantum computing device of claim 1 , wherein the resonator is formed from a first material having grooves in a top surface with a second material formed in the grooves, wherein the second material creates a strain in a crystalline structure of the first material to generate the electro-optic effect in the resonator.
4. The quantum computing device of claim 3 , wherein the resonator comprises an optical disc structure.
5. The quantum computing device of claim 3 , wherein the resonator comprises an optical ring structure.
6. The quantum computing device of claim 3 , wherein the first material includes silicon and the second material includes silicon germanium.
7. The quantum computing device of claim 1 , wherein the central pin comprises a surface facing toward the resonator, the surface having a ridge along an outer circumference.
8. The quantum computing device of claim 7 , wherein the ridge on the central pin is positioned directly on the resonator.
9. The quantum computing device of claim 7 , wherein the ridge on the central pin is positioned above the resonator to provide a small gap between the ridge and the resonator.
10. The quantum computing device of claim 1 , wherein the first frequency is a microwave frequency and the second frequency is an optical frequency.
11. The quantum computing device of claim 1 , wherein the central pin is coaxial with the cavity.
12. The quantum computing device of claim 1 , wherein the transducer further comprises a second cavity underneath the resonator having a same diameter as the cavity in the substrate.
13. The quantum computing device of claim 1 , wherein the transducer is coupled to the qubit via a superconducting channel disposed within the substrate.
14. The quantum computing device of claim 1 , wherein the cavity includes a radius of about 2.5 millimeters and the central pin includes a radius of about 2 millimeters.
15. The quantum computing device of claim 1 , wherein the resonator includes a diameter that provides three modes at frequencies ω op −ω q for a red-sideband, ω op for a carrier, and ω op +ω q for a blue-side band, with ω q being a microwave frequency of a microwave resonator.
16. A quantum computing device, comprising:
a qubit configured to provide a first signal at a first frequency;
a transducer coupled to the qubit, comprising:
a substrate having a cylindrical cavity with a diameter that supports whispering gallery modes at the first frequency;
a central pin in the cavity, wherein an outer surface of the central pin and an inner surface of the cavity have a superconducting film formed directly thereon; and
a resonator directly under the central pin, having a crystalline structure that generates an electro-optic effect when exposed to electrical fields, wherein an electric field of the input signal modulates a second signal at a second frequency in the resonator via the electro-optic effect, the resonator being formed from a first material having grooves in a top surface with a second material formed in the grooves, wherein the second material creates a strain in a crystalline structure of the first material to generate the electro-optic effect in the resonator; and
a waveguide, optically coupled to the resonator, that is configured to convey the modulated second signal away from the resonator.
17. The quantum computing device of claim 16 , wherein the first material includes silicon and the second material includes silicon germanium.
18. The quantum computing device of claim 16 , wherein the central pin comprises a surface facing toward the resonator, the surface having a ridge along an outer circumference.
19. The quantum computing device of claim 16 , wherein the transducer further comprises a second cavity underneath the resonator having a same diameter as the cavity in the substrate.
20. The quantum computing device of claim 16 , wherein the transducer is coupled to the qubit via a superconducting channel disposed within the substrate.