Oleg A. Mukhanov

Discriminating the Phase of a Coherent Tone with a Flux-Switchable Superconducting Circuit

  1. Luigi Di Palma,
  2. Alessandro Miano,
  3. Pasquale Mastrovito,
  4. Davide Massarotti,
  5. Marco Arzeo,
  6. Giovanni Piero Pepe,
  7. Francesco Tafuri,
  8. and Oleg A. Mukhanov
We propose a new phase detection technique based on a flux-switchable superconducting circuit, the Josephson digital phase detector (JDPD), which is capable of discriminating between
two phase values of a coherent input tone. When properly excited by an external flux, the JDPD is able to switch from a single-minimum to a double-minima potential and, consequently, relax in one of the two stable configurations depending on the phase sign of the input tone. The result of this operation is digitally encoded in the occupation probability of a phase particle in either of the two JDPD wells. In this work, we demonstrate the working principle of the JDPD up to a frequency of 400 MHz with a remarkable agreement with theoretical expectations. As a future scenario, we discuss the implementation of this technique to superconducting qubit readout. We also examine the JDPD compatibility with the single-flux-quantum architecture, employed to fast-drive and measure the device state.
arxiv pdf

Symmetric Traveling Wave Parametric Amplifier

  1. Alessandro Miano,
  2. and Oleg A. Mukhanov
We developed and experimentally tested a Symmetric Traveling Wave Parametric Amplifier (STWPA) based on Three-Wave Mixing, using the new concept of a Symmetric rf- SQUID. This allows
to fully control the second and third order nonlinearities of the STWPA by applying external currents. In this way, the optimal bias point can be reached, taking into account both phase mismatch and pump depletion minimization. The structure was tested at 4.2K, showing a 4GHz bandwidth and a maximum estimated gain of 17dB. STWPA showed also great flexibility, allowing up-down conversion mixer operations and rf-controlled switch.
arxiv pdf