Ken Inoue

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.
arxiv pdf

Exploiting dynamic quantum circuits in a quantum algorithm with superconducting qubits

  1. Antonio D. Corcoles,
  2. Maika Takita,
  3. Ken Inoue,
  4. Scott Lekuch,
  5. Zlatko K. Minev,
  6. Jerry M. Chow,
  7. and Jay M. Gambetta
The execution of quantum circuits on real systems has largely been limited to those which are simply time-ordered sequences of unitary operations followed by a projective measurement.
As hardware platforms for quantum computing continue to mature in size and capability, it is imperative to enable quantum circuits beyond their conventional construction. Here we break into the realm of dynamic quantum circuits on a superconducting-based quantum system. Dynamic quantum circuits involve not only the evolution of the quantum state throughout the computation, but also periodic measurements of a subset of qubits mid-circuit and concurrent processing of the resulting classical information within timescales shorter than the execution times of the circuits. Using noisy quantum hardware, we explore one of the most fundamental quantum algorithms, quantum phase estimation, in its adaptive version, which exploits dynamic circuits, and compare the results to a non-adaptive implementation of the same algorithm. We demonstrate that the version of real-time quantum computing with dynamic circuits can offer a substantial and tangible advantage when noise and latency are sufficiently low in the system, opening the door to a new realm of available algorithms on real quantum systems.
arxiv pdf