A near-ideal degenerate parametric amplifier

  1. Daniel J. Parker,
  2. Mykhailo Savytskyi,
  3. Wyatt Vine,
  4. Arne Laucht,
  5. Timothy Duty,
  6. Andrea Morello,
  7. Arne L. Grimsmo,
  8. and Jarryd J. Pla
Degenerate parametric amplifiers (DPAs) exhibit the unique property of phase-sensitive gain and can be used to noiselessly amplify small signals or squeeze field fluctuations beneath
the vacuum level. In the microwave domain, these amplifiers have been utilized to measure qubits in elementary quantum processors, search for dark matter, facilitate high-sensitivity spin resonance spectroscopy and have even been proposed as the building blocks for a measurement based quantum computer. Until now, microwave DPAs have almost exclusively been made from nonlinear Josephson junctions, which exhibit high-order nonlinearities that limit their dynamic range and squeezing potential. In this work we investigate a new microwave DPA that exploits a nonlinearity engineered from kinetic inductance. The device has a simple design and displays a dynamic range that is four orders of magnitude greater than state-of-the-art Josephson DPAs. We measure phase sensitive gains up to 50 dB and demonstrate a near-quantum-limited noise performance. Additionally, we show that the higher-order nonlinearities that limit other microwave DPAs are almost non-existent for this amplifier, which allows us to demonstrate its exceptional squeezing potential by measuring the deamplification of coherent states by as much as 26 dB.

Investigation of nonlinear effects in Josephson parametric oscillators used in circuit QED

  1. Philip Krantz,
  2. Yarema Reshitnyk,
  3. Waltraut Wustmann,
  4. Jonas Bylander,
  5. Simon Gustavsson,
  6. William D. Oliver,
  7. Timothy Duty,
  8. Vitaly Shumeiko,
  9. and Per Delsing
We experimentally study the behavior of a parametrically pumped nonlinear oscillator, which is based on a superconducting lambda /4 resonator, and is terminated by a flux-tunable SQUID.
We extract parameters for two devices. In particular, we study the effect of the nonlinearities in the system and compare to theory. The Duffing nonlinearity, \alpha, is determined from the probe-power dependent frequency shift of the oscillator, and the nonlinearity, \beta, related to the parametric flux pumping, is determined from the pump amplitude for the onset of parametric oscillations. Both nonlinearities depend on the parameters of the device and can be tuned in-situ by the applied dc flux. We also suggest how to cancel the effect of \beta by adding a small dc flux and a pump tone at twice the pump frequency.