PRX Quantum (Feb 2024)

Using Cryogenic CMOS Control Electronics to Enable a Two-Qubit Cross-Resonance Gate

  • Devin Underwood,
  • Joseph A. Glick,
  • Ken Inoue,
  • David J. Frank,
  • John Timmerwilke,
  • Emily Pritchett,
  • Sudipto Chakraborty,
  • Kevin Tien,
  • Mark Yeck,
  • John F. Bulzacchelli,
  • Chris Baks,
  • Raphael Robertazzi,
  • Matthew Beck,
  • Rajiv V. Joshi,
  • Dorothy Wisnieff,
  • Scott Lekuch,
  • Brian P. Gaucher,
  • Daniel J. Friedman,
  • Pat Rosno,
  • Daniel Ramirez,
  • Jeff Ruedinger

DOI
https://doi.org/10.1103/PRXQuantum.5.010326
Journal volume & issue
Vol. 5, no. 1
p. 010326

Abstract

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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 14-nm fin field-effect transistor (FinFET) technology was used to generate and sequence qubit control wave forms and demonstrate a two-qubit cross-resonance gate between fixed-frequency transmons. The controller was thermally anchored to the T=4 K 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 ϵ_{1Q}=8×10^{−4} and a two-qubit error per gate of ϵ_{2Q}=1.4×10^{−2} were shown. A drive-induced Z rotation was observed by way of a rotary-echo experiment; this observation is consistent with the expected qubit behavior given the measured excess local-oscillator (LO) leakage from the CMOS chip. The effect of spurious drive-induced Z errors was numerically evaluated with a two-qubit model Hamiltonian and shown to be in good agreement with the measured RB data. The modeling results suggest that the Z error varies linearly with the pulse amplitude.