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US-12624996-B2 - Efficient source of shaped single photons based on an integrated diamond nanophotonic system

US12624996B2US 12624996 B2US12624996 B2US 12624996B2US-12624996-B2

Abstract

Sources of shaped single photons based on an integrated diamond nanophotonic system are provided.

Inventors

  • Can-Paul Mithat Horst Knaut
  • Mikhail D. Lukin
  • Marko Loncar
  • Erik Nils Knall
  • Rivka Bekenstein
  • Daniel Rimoli Assumpcao

Assignees

  • PRESIDENT AND FELLOWS OF HARVARD COLLEGE

Dates

Publication Date
20260512
Application Date
20221219

Claims (14)

  1. 1 . A device, comprising: a diamond photonic crystal comprising a first mirror region, a second mirror region, and a defect region interposed between the first mirror region and the second mirror region, wherein: the first mirror region has a first set of unit cells, and the second mirror region has a second set of unit cells different from the first set of unit cells, and wherein the defect region comprises exactly one silicon-vacancy center (SiV).
  2. 2 . The device of claim 1 , further comprising a magnetic field source configured to apply a magnetic field orthogonal to a symmetry axis of the silicon-vacancy center (SiV).
  3. 3 . A system for producing temporally shaped single-photon pulses, the system comprising: at least one coherent light source, the at least one coherent light source configured to emit a control pulse having a strength and temporal shape; a diamond photonic crystal positioned to receive the control pulse, and configured to emit a single-photon pulse having a temporal shape determined by the strength and temporal shape of the control pulse; and an optical waveguide positioned to receive the single-photon pulse, wherein: the diamond photonic crystal comprises a first mirror region, a second mirror region, and a defect region interposed between the first mirror region and the second mirror region, the first mirror region has a first set of unit cells, and the second mirror region has a second set of unit cells different from the first set of unit cells, and wherein the defect region comprises exactly one silicon-vacancy center (SiV).
  4. 4 . The system of claim 3 , further comprising a dilution refrigerator, wherein the diamond photonic crystal is positioned in the dilution refrigerator.
  5. 5 . The system of claim 4 , wherein the dilution refrigerator is configured to maintain a temperature of about 50 mK.
  6. 6 . The system of claim 3 , wherein the optical waveguide comprises an optical fiber.
  7. 7 . The system of claim 6 , wherein the optical fiber is tapered.
  8. 8 . The system of claim 3 , wherein the at least one coherent light source is further configured to emit an initialization pulse to prepare an initial spin state of the silicon-vacancy center (SiV).
  9. 9 . The system of claim 3 , wherein the at least one coherent light source comprises an acousto-optic modulator (AOM) configured to apply the temporal shape to the control pulse.
  10. 10 . The system of claim 3 , further comprising a free-space filter positioned to receive the shaped single-photon pulse and separate light from the at least one coherent light source therefrom.
  11. 11 . A method of producing temporally shaped single-photon pulses, comprising: directing a control pulse from at least one coherent light source to a diamond photonic crystal, the control pulse having a strength and a temporal shape; and receiving from the diamond photonic crystal, in response to the control pulse, a single-photon pulse having a temporal shape determined by the strength and temporal shape of the control pulse, wherein: the diamond photonic crystal comprises a first mirror region, a second mirror region, and a defect region interposed between the first mirror region and the second mirror region, the first mirror region has a first set of unit cells, and the second mirror region has a second set of unit cells different from the first set of unit cells, and wherein the defect region comprises exactly one silicon-vacancy center (SiV).
  12. 12 . The method of claim 11 , further comprising cooling the diamond photonic crystal to a temperature of about 50 mK.
  13. 13 . The method of claim 11 , further comprising applying a magnetic field orthogonal to a symmetry axis of the silicon-vacancy center (SiV).
  14. 14 . The method of claim 11 , further comprising: separating light emitted by the at least one coherent light source from the shaped single-photon pulse.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63/290,842, filed Dec. 17, 2021, which is hereby incorporated by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under 2012023 and 1734011 and 1941583 awarded by National Science Foundation (NSF) and under DE-SC0020115 awarded by U.S. Department of Energy (DOE) and under FA9550-17-1-0002 and FA9550-16-1-0323 awarded by U.S. Air Force Office of Scientific Research (AFOSR). The government has certain rights in this invention. BACKGROUND Embodiments of the present disclosure relate to nanophotonic systems, and more specifically, to efficient sources of shaped single photons. BRIEF SUMMARY According to embodiments of the present disclosure, sources of shaped single photons based on an integrated diamond nanophotonic system are provided. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1A is a photon creation schematic. The four-level system of the SiV spin is coherently driven by alternating initialization (Ωinit) and photon generation (Ωcont) optical pulses, producing a train of temporally shaped photons which are efficiently collected with an overcoupled nanophotonic cavity. FIG. 1B is a measurement setup schematic. A nanophotonic cavity containing an SiV is cooled to 50 mK in a dilution refrigerator and pumped to coherently create single, arbitrarily-shaped photons. Pump pulses are shaped using an acousto-optic modulator, and pump light is filtered out of the single-photon stream by a free space Fabry-Pérot cavity. FIG. 2A: Photon extraction efficiency is shown in the color plot as a function of cavity-waveguide coupling κw and unwanted cavity loss rate κ_s. Contours aid readability of color map. Optimal extraction efficiency is maximized by trading off atom-photon interaction probability, proportional to (κs+κw)−1, for a higher cavity-waveguide coupling rate κw. The dashed-dot line cut corresponds to κs=89 GHz, the unwanted loss rate of this device, which is determined by fabrication imperfections. The red star highlights this device with waveguide coupling rate κw=240 GHz, which is nearly optimal for the given κs. FIG. 2B is a scanning electron micrograph (SEM) of the nanophotonic cavity is overlaid with the simulated electric field, and loss rates are labeled, where κs=κscat+κleft. FIG. 2C: The simulated quasipotential shape of the cavity shows that there is a lower and shorter potential barrier on the weak mirror side. This corresponds to the coupling to the right waveguide being the dominant loss rate (κw>>κs). FIGS. 3A-F illustrate pulse-shaped single-photon generation. FIGS. A, C, and E display the temporal profile of the coherent control pulse and detected single photon. FIG. 3A: A square control pulse produces an exponentially decaying photon. FIG. 3B: A Gaussian single photon. FIG. 3C: A single photon distributed over ten time bins (FIG. 3E). FIGS. B, D, and F display the normalized second order correlation of photon arrivals for the exponential, Gaussian, and ten peaked photons respectively. The insets show a zoomed-in window around τ=0, which is integrated to calculate g(2)(0). FIG. 4: Statistics of consecutive n-photon streams detected during a 24-hour acquisition at a 405 kHz repetition rate and 57% average duty cycle, showing detection of up to 11 photons in a row. Exponential decay fit indicates a total source-to-detector efficiency of 14.9%. FIGS. 5A-D: Hyperfine splitting due to the 29Si nuclear spin (FIG. 5A) gives rise to a four-level ground state manifold. Pumping on the electron-spin flipping transition with Ωcont results in the generation of photons with two nuclear-state dependent frequencies ν⬆ and ν⬇. FIG. 5B: Sweeping the control pulse frequency selectively tunes ν⬆ and ν⬇ into resonance with the filter cavity, which enables the measurement of the spectrum of the emitted photons. FIG. 5C: Pulse sequence for attempting to measure either two consecutive photons at nuclear-state dependent frequencies ν⬇ and ν⬇ or at nuclear-state dependent frequencies ν⬇ and ν⬆. FIG. 5D: (upper curve) g⇓⇓(2)(τ) auto-correlation measurements of the photons emitted at ν⬇ show antibunching at zero time delay, and bunching after emission of 113.8±3.8 photons (1.48 ms timescale). (lower curve) g⇓⇑(2)(τ) cross-correlation function for the two consecutively emitted photons at ν⬆ and ν⬇ shows anti-bunching after emission of 110.6±2.4 photons, suggesting that the nuclear polarization is preserved for repeated generation of up to 110 photons. FIG. 6 depicts a classical computing node according to embodiments of the present disclosure. FIG. 7A-D: photonic cavities. FIG. 8A: Quasipotential for this device. FIG. 8B: Relative hole geometry parameters in units of the nominal lattice constant. FIG. 8C: Scale depiction of cavity top view. FIG. 8D: Simulated photonic band-structure diagrams for representative