Clock generation for a photonic quantum computer comprising a photon-pair source to convert the converted electrical pulses into a plurality of clock signals at a first repetition rate

1. A system for generating clock signals for a photonic quantum computing system, the system comprising:

a pump photon source configured to generate a plurality of pump photon pulses at a first repetition rate;

a photon-pair source optically coupled to the pump photon source, the photon-pair source configured to:

convert a subset of the plurality of pump photon pulses into photon pairs;

output the photon pairs; and

output a portion of each pump photon pulse of the plurality of pump photon pulses;

a photodetector optically coupled to the photon-pair source and configured to:

receive the portion of each pump photon pulse of the plurality of pump photon pulses; and

converting the portion of each pump photon pulse of the plurality of pump photon pulses into a respective electrical pulse of a plurality of electrical pulses; and

a clock generator electrically coupled to the photodetector and configured to convert the plurality of electrical pulses into a plurality of clock signals at the first repetition rate.

2. The system of claim 1 wherein the photon-pair source, the photodetector, the clock generator, and the photonic quantum computing system are disposed inside a cryostat and the pump photon source is disposed outside the cryostat.

3. The system of claim 1 wherein each of the photon pairs comprises a signal photon and a heralding photon, and one of the signal photon or the heralding photon is used by the photonic quantum computing system as a qubit.

4. The system of claim 1 further comprising a waveguide optically coupled to the pump photon source and the photon-pair source.

5. The system of claim 1 wherein each of the photon pairs comprises a signal photon and a heralding photon, and one of the signal photon or the heralding photon is used by the photonic quantum computing system as a qubit.

6. A system comprising:

a pump photon source;

a photon-pair source optically coupled to the pump photon source, wherein the photon-pair source is configured to:

receive a plurality of pump photon pulses from the pump photon source;

convert a first portion of the plurality of pump photon pulses into a photon pair;

output the photon pair; and

output a second portion of the plurality of pump photon pulses; and

a photodetector optically coupled to the photon-pair source and configured to generate a plurality of electrical pulses in response to detection of at least a portion of the plurality of pump photon pulses.

7. The system of claim 6 further comprising a clock generator coupled to the photodetector, the clock generator configured to convert the plurality of electrical pulses into a plurality of clock signals for a photonic quantum computing system.

8. The system of claim 7 wherein the photon-pair source and the photodetector are implemented in a photonic integrated circuit (PIC) and the clock generator is implemented in an electronic integrated circuit (EIC).

9. The system of claim 8 wherein the PIC and EIC are fusion bonded.

10. The system of claim 7 wherein the photon-pair source, the photodetector, and the clock generator are implemented on a same substrate structure.

11. The system of claim 10 wherein the same substrate structure comprises a fused PIC and EIC.

12. The system of claim 7 wherein the photon-pair source, the photodetector, the clock generator, and the photonic quantum computing system are disposed on a single chip disposed inside a cryostat.

13. The system of claim 12 wherein the pump photon source is disposed outside the cryostat.

14. The system of claim 6 wherein the photon pair comprises a signal photon and a heralding photon, and one of the signal photon or the heralding photon is used by a quantum computing system as a qubit.

15. The system of claim 6 wherein the photon-pair source converts the first portion of the plurality of pump photon pulses into the photon pair non-deterministically.

16. The system of claim 6 wherein the photon-pair source comprises:

a first waveguide for receiving the plurality of pump photon pulses generated by the pump photon source;

a resonator optically coupled to the first waveguide so that a portion of each pump photon pulse of the plurality of pump photon pulses is coupled into the resonator, the resonator comprising a nonlinear optical material for converting the first portion of the plurality of pump photon pulses into the photon pair; and

a second waveguide optically coupled to the resonator so that the photon pair converted from the plurality of pump photon pulses are coupled thereto.

17. The system of claim 16 wherein the resonator comprises one or more ring resonators.

18. The system of claim 16 wherein the second portion of the plurality of pump photon pulses is coupled into the second waveguide and output by the second waveguide.

19. The system of claim 18 further comprising a pump rejecter optically coupled to the second waveguide of the photon-pair source, the pump rejecter configured to:

receive the photon pair and the second portion of the plurality of pump photon pulses;

output the photon pair through a first output port; and

output the second portion of the plurality of pump photon pulses through a second output port optically coupled to the photodetector.

20. The system of claim 19 wherein the pump rejecter comprises a spectral filter.