Scalable feedback control of single-photon sources for photonic quantum technologies

Patent metadata

Field	Value
Publication number	US-11237454-B2
Application number	US-201916680908-A
Country	US
Kind code	B2
Filing date	Nov 12, 2019
Priority date	Nov 12, 2018
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Typically, quantum systems are very sensitive to environmental fluctuations, and diagnosing errors via measurements causes unavoidable perturbations. Here, an in situ frequency-locking technique monitors and corrects frequency variations in single-photon sources based on resonators. By using the classical laser fields used for photon generation as probes to diagnose variations in the resonator frequency, the system applies feedback control to correct photon frequency errors in parallel to the optical quantum computation without disturbing the physical qubit. Our technique can be implemented on a silicon photonic device and with sub 1 pm frequency stabilization in the presence of applied environmental noise, corresponding to a fractional frequency drift of <1% of a photon linewidth. These methods can be used for feedback-controlled quantum state engineering. By distributing a single local oscillator across a one or more chips, our approach enables frequency locking of many single photon sources for large-scale photonic quantum technologies.

First claim

The invention claimed is:

1. A method of generating frequency-stabilized single photons, the method comprising:
pumping a microring resonator comprising a nonlinear material with a pump beam to generate a single photon;
coupling the single photon and the pump beam out of the microring resonator;
filtering the single photon from the pump beam;
detecting an intensity of the pump beam; and
tuning the microring resonator based on the intensity of the pump beam to stabilize a wavelength of a resonance of the microring resonator,
wherein the pump beam comprises pump light at a first wavelength and pump light at a second wavelength greater than the first wavelength and the single photon is at a wavelength between the first wavelength and the second wavelength.

2. The method of claim 1 , wherein tuning the microring resonator comprises locking the first wavelength to a wavelength of a +n resonance of the microring resonator, where n is a positive integer.

3. The method of claim 2 , wherein tuning the microring resonator comprises locking the second wavelength to a wavelength of a −n resonance of the microring resonator.

4. The method of claim 1 , wherein tuning the microring resonator comprises stabilizing the wavelength of the resonance to within 1 picometer of a desired wavelength.

5. The method of claim 1 , wherein tuning the microring resonator comprises stabilizing the wavelength of the resonance to within 1% of a linewidth of the resonance.

6. The method of claim 1 , wherein the microring resonator is a first microring resonator, the pump beam is a first pump beam, and the single photon is a first single photon, and further comprising:
pumping a second microring resonator with a second pump beam to generate a second single photon;
coupling the second single photon and the second pump beam out of the microring resonator;
filtering the second single photon from the second pump beam;
detecting an intensity of the second pump beam; and
tuning the second microring resonator based on the intensity of the second pump beam to stabilize a resonance wavelength of the second microring resonator.

7. The method of claim 6 , further comprising:
emitting pump light from a laser; and
splitting the pump light into at least part of the first pump beam and at least part of the second pump beam.

8. The method of claim 6 , further comprising:
adjusting a relative phase between the first single photon and the second single photon; and
interfering the first single photon with the second single photon to produce an engineered quantum state.

9. A frequency-stabilized single-photon source comprising:
a microring resonator with a nonlinear material to generate a single photon in response to being pumped with a pump beam;
a filter, in optical communication with the microring resonator, to filter the single photon from the pump beam;
a detector, in optical communication with the filter, to detect an intensity of the pump beam;
a phase shifter, operably coupled to the detector and the microring resonator, to tune a wavelength of a resonance of the microring resonator based on the intensity of the pump beam;
a first pump laser to generate pump light at a first wavelength;
a second pump laser to generate pump light at a second wavelength greater than the first wavelength; and
a beam combiner, in optical communication with the first pump laser and the second pump laser, to combine the pump light at the first wavelength and the pump light at the second wavelength to form the pump beam.

10. The frequency-stabilized single-photon source of claim 9 , wherein the phase shifter is configured to lock the first wavelength to a wavelength of a +n resonance of the microring resonator, where n is a positive integer.

11. The frequency-stabilized single-photon source of claim 10 , wherein the phase shifter is further configured to lock the second wavelength to a wavelength of a −n resonance of the microring resonator.

12. The frequency-stabilized single-photon source of claim 9 , wherein the phase modulator is configured to stabilize the wavelength of the resonance to within 1 picometer of a desired wavelength.

13. The frequency-stabilized single-photon source of claim 9 , wherein the phase modulator is configured to stabilize the wavelength of the resonance to within 1% of a linewidth of the resonance.

14. A frequency-stabilized single-photon source, comprising:
a first microring resonator with a nonlinear material to generate a first single photon in response to being pumped with a first pump beam;
a first filter, in optical communication with the first microring resonator, to filter the first single photon from the first pump beam;
a first detector, in optical communication with the first filter, to detect an intensity of the first pump beam;
a first phase shifter, operably coupled to the first detector and the first microring resonator, to tune a wavelength of a resonance of the first microring resonator based on the intensity of the first pump beam;
a second microring resonator to generate a second single photon in response to being pumped with a second pump beam;
a second filter, in optical communication with the second microring resonator, to filter the second single photon from the second pump beam;
a second detector, in optical communication with the second filter, to detect an intensity of the second pump beam; and
a second phase shifter, operably coupled to the second detector and the second microring resonator, to tune a resonance frequency of the second microring resonator based on the intensity of the second pump beam.

15. The frequency-stabilized single-photon source of claim 14 , further comprising:
a differential phase shifter, in optical communication with the first filter, to adjust a relative phase between the first single photon and the second single photon; and
a beam combiner, in optical communication with the phase shifter and the second filter, to interfere the first single photon with the second single photon to produce an engineered quantum state.

16. A photonic device comprising:
a substrate;
an array of microring resonators, integrated on the substrate and comprising χ 3 nonlinear material, to generate single photons at a signal wavelength in response to being pumped with pump light at a first pump wavelength greater than the signal wavelength and a second pump wavelength less than the signal wavelength;
an array of filters integrated on the substrate, each filter in the array of filters in optical communication with a corresponding microring resonator in the array of microring resonators and configured to filter the single photon from light at the first pump wavelength and at the second pump wavelength coupled out of the corresponding microring resonator;
an array of detectors in optical communication with the array of filters, each detector in the array of detectors in optical communication with a corresponding filter in the array of filters and configured to detect an intensity of the light at the first pump wavelength and/or at the second pump wavelength filtered by the corresponding filter; and
an array of thermo-optic modulators integrated on the substrate, each thermo-optic modulator in the array of thermo-optic modulators operably coupled to a corresponding detector in the array of detectors and in thermal communication with the corresponding microring resonator and configured to stabilize a resonance frequency of the corresponding microring resonator based on the intensity detected by the corresponding detector.

17. The photonic device o

Assignees

• Massachusetts Inst Technology

Inventors

• Carolan Jacques Johannes
• Chakraborty Uttara
• Harris Nicholas C
• Pant Mihir
• Englund Dirk Robert

Classifications

• G02F2203/50

  Phase-only modulation · CPC title

• H01S3/094003

  the pumped medium being a fibre · CPC title

• G02F1/365

  in an optical waveguide structure (G02F1/377, {G02F1/395} take precedence) · CPC title

• H01S3/1628

  characterised by a semiconducting matrix · CPC title

• G02F2201/06

  integrated waveguide · CPC title