Joerg Bochmann

Fabrication and Characterization of Aluminum Airbridges for Superconducting Microwave Circuits

  1. Zijun Chen,
  2. Anthony Megrant,
  3. Julian Kelly,
  4. Rami Barends,
  5. Joerg Bochmann,
  6. Yu Chen,
  7. Ben Chiaro,
  8. Andrew Dunsworth,
  9. Evan Jeffrey,
  10. Joshua Mutus,
  11. Peter O'Malley,
  12. Charles Neill,
  13. Pedram Roushan,
  14. Daniel Sank,
  15. Amit Vainsencher,
  16. James Wenner,
  17. Theodore White,
  18. Andrew Cleland,
  19. and John Martinis
Superconducting microwave circuits based on coplanar waveguides (CPW) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting
airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers.
arxiv pdf

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