Using Cryogenic CMOS Control Electronics To Enable A Two-Qubit Cross-Resonance Gate

  1. Devin L. Underwood,
  2. Joseph A. Glick,
  3. Ken Inoue,
  4. David J. Frank,
  5. John Timmerwilke,
  6. Emily Pritchett,
  7. Sudipto Chakraborty,
  8. Kevin Tien,
  9. Mark Yeck,
  10. John F. Bulzacchelli,
  11. Chris Baks,
  12. Pat Rosno,
  13. Raphael Robertazzi,
  14. Matthew Beck,
  15. Rajiv V. Joshi,
  16. Dorothy Wisnieff,
  17. Daniel Ramirez,
  18. Jeff Ruedinger,
  19. Scott Lekuch,
  20. Brian P. Gaucher,
  21. and Daniel J. Friedman
Qubit control electronics composed of CMOS circuits are of critical interest for next generation quantum computing systems. A CMOS-based application specific integrated circuit (ASIC) fabricated in 14nm FinFET technology was used to generate and sequence qubit control waveforms and demonstrate a two-qubit cross resonance gate between fixed frequency transmons. The controller was thermally anchored to the T = 4K stage of a dilution refrigerator and the measured power was 23 mW per qubit under active control. The chip generated single–side banded output frequencies between 4.5 and 5.5 GHz with a maximum power output of -18 dBm. Randomized benchmarking (RB) experiments revealed an average number of 1.71 instructions per Clifford (IPC) for single-qubit gates, and 17.51 IPC for two-qubit gates. A single-qubit error per gate of ϵ1Q=8e-4 and two-qubit error per gate of ϵ2Q=1.4e-2 is shown. A drive-induced Z-rotation is observed by way of a rotary echo experiment; this observation is consistent with expected qubit behavior given measured excess local oscillator (LO) leakage from the CMOS chip. The effect of spurious drive induced Z-errors is numerically evaluated with a two-qubit model Hamiltonian, and shown to be in good agreement with measured RB data. The modeling results suggest the Z-error varies linearly with pulse amplitude.
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