Xin Zhou

Microwave Optomechanically Induced Transparency and Absorption

  1. Sumit Kumar,
  2. Dylan Cattiaux,
  3. Eddy Collin,
  4. Andrew Fefferman,
  5. and Xin Zhou
High-quality microwave amplifiers and notch-filters can be made from microwave optomechanical systems in which a mechanical resonator is coupled to a microwave cavity by radiation pressure.
These amplifiers and filters rely on optomechanically induced transparency (OMIT) and absorption (OMIA), respectively. Such devices can amplify microwave signals with large, controllable gain, high dynamic range and very low noise. Furthermore, extremely narrowband filters can be constructed with this technique. We briefly review previous measurements of microwave OMIT and OMIA before reporting our own measurements of these phenomena, which cover a larger parameter space than has been explored in previous works. We find excellent agreement between our measurements and the predictions of input/output theory, thereby guiding further development of microwave devices based on nanomechanics.
arxiv pdf

Manipulating Fock states of a harmonic oscillator while preserving its linearity

  1. Kristinn Juliusson,
  2. Simon Bernon,
  3. Xin Zhou,
  4. Vivien Schmitt,
  5. Hélène le Sueur,
  6. Patrice Bertet,
  7. Denis Vion,
  8. Mazyar Mirahimi,
  9. Pierre Rouchon,
  10. and Daniel Esteve
We present a new scheme for controlling the quantum state of a harmonic oscillator by coupling it to an anharmonic multilevel system (MLS) with first to second excited state transition
frequency on-resonance with the oscillator. In this scheme that we call „ef-resonant“, the spurious oscillator Kerr non-linearity inherited from the MLS is very small, while its Fock states can still be selectively addressed via an MLS transition at a frequency that depends on the number of photons. We implement this concept in a circuit-QED setup with a microwave 3D cavity (the oscillator, with frequency 6.4 GHz and quality factor QO=2E-6) embedding a frequency tunable transmon qubit (the MLS). We characterize the system spectroscopically and demonstrate selective addressing of Fock states and a Kerr non-linearity below 350 Hz. At times much longer than the transmon coherence times, a non-linear cavity response with driving power is also observed and explained.
arxiv pdf