Measuring high-order phonon correlations in an optomechanical resonator

Measuring high-order phonon correlations in an optomechanical resonator
Y. S. S. Patil, J. Yu, S. Frazier, Y. Wang, K. Johnson, J. Fox, J. Reichel, and J. G. E. Harris
Physical Review Letters 128, 183601 (2022)
arXiv:2201.07340 (2022)

• Abstract

  We use single photon detectors to probe the motional state of a superfluid $^4\text$ resonator of mass $\sim1$ ng. The arrival times of Stokes and anti-Stokes photons (scattered by the resonator's acoustic mode) are used to measure the resonator's phonon coherences up to the fourth order. By postselecting on photon detection events, we also measure coherences (up to the third order) in the resonator when $\le 3$ phonons have been added or subtracted. These measurements are found to be consistent with predictions that assume the acoustic mode to be in thermal equilibrium with a bath through a Markovian coupling.

• Bibtex

  @article{patilCorrelations2022,
  title = {Measuring High-Order Phonon Correlations in an Optomechanical Resonator},
  author = {Patil, Y. S. S. and Yu, J. and Frazier, S. and Wang, Y. and Johnson, K. and Fox, J. and Reichel, J. and Harris, J. G. E.},
  journal = {Phys. Rev. Lett.},
  volume = {128},
  issue = {18},
  pages = {183601},
  numpages = {6},
  year = {2022},
  month = {May},
  publisher = {American Physical Society},
  doi = {10.1103/PhysRevLett.128.183601},
  url = {https://link.aps.org/doi/10.1103/PhysRevLett.128.183601}
  }

(a) Device schematic: A fiber-based Fabry-Perot cavity is filled with superfluid $^4$He. Blue shading denotes the instantaneous $^4$He density in an acoustic mode. Orange denotes the optical mode intensity. (b) Optical schematic showing the two drive lasers (red and blue paths), optomechanical cavity (OMC, black dashed box), acoustically scattered photons (green path), two signal filter cavities (green) and the two SPDs. The filter cavities (red and blue) before the OMC are used to suppress laser phase noise. (c) Optical spectrum showing the frequencies of the lasers, scattered photons, and filters, all with respect to the OMC's optical resonance. (d) Photon count rate spectrum measured as a function of the drive laser detuning $\Delta$, with $P_\text{in} = 400$ nW.