Irfan Siddiqi

Design and characterization of a lumped element single-ended superconducting microwave parametric amplifier with on-chip flux bias line

  1. Josh Mutus,
  2. Ted White,
  3. Evan Jeffery,
  4. Daniel Sank,
  5. Rami Barends,
  6. Joerg Bochmann,
  7. Yu Chen,
  8. Zijun Chen,
  9. Ben Chiaro,
  10. Andrew Dunsworth,
  11. Julian Kelly,
  12. Anthony Megrant,
  13. Charles Neill,
  14. Peter O'malley,
  15. Pedram Roushan,
  16. Amit Vainsencher,
  17. Jim Wenner,
  18. Irfan Siddiqi,
  19. Rajamani Vijayaraghavan,
  20. Andrew Cleland,
  21. and John Martinis
We demonstrate a lumped-element Josephson Parametric Amplifier (LJPA), using a single-ended design that includes an on-chip, high-bandwidth flux bias line. The amplifier can be pumped
into its region of parametric gain through either the input port or through the flux bias line. Broadband amplification is achieved at a tunable frequency $\omega/2 \pi$ between 5 to 7 GHz with quantum-limited noise performance, a gain-bandwidth product greater than 500 MHz, and an input saturation power in excess of -120 dBm. The bias line allows fast frequency tuning of the amplifier, with variations of hundreds of MHz over time scales shorter than 10 ns.
arxiv pdf

Analog Superconducting Quantum Simulator for Holstein Polarons

  1. Feng Mei,
  2. Vladimir M. Stojanovic,
  3. Irfan Siddiqi,
  4. and Lin Tian
We propose an analog quantum simulator for the Holstein molecular-crystal model based on a dispersive superconducting circuit QED system composed of transmon qubits and microwave resonators.
By varying the circuit parameters, one can readily access both the adiabatic and the anti-adiabatic regimes of this model, and realize the coupling strengths required for small-polaron formation. We present a pumping scheme for preparing small-polaron states of arbitrary quasimomentum within time scales much shorter than the qubit decoherence time. The ground state of the system is characterized by anomalous amplitude fluctuation and measurement-based momentum squeezing in the resonator modes.
arxiv pdf