Sarma B, Hartmann M (2025)
Publication Language: English
Publication Type: Journal article
Publication year: 2025
Book Volume: 23
Article Number: 014015
Journal Issue: 1
DOI: 10.1103/PhysRevApplied.23.014015
Fast quantum gates are crucial not only for the contemporary era of noisy intermediate-scale quantum devices but also for the prospective development of practical fault-tolerant quantum computing. Leakage errors, which arise from data qubits jumping beyond the confines of the computational subspace, are the main challenges in realizing nonadiabatically driven, fast gates. In this work, we propose and illustrate the usefulness of reinforcement learning (RL) to generate fast two-qubit gates in practical multilevel superconducting qubits. In particular, we show that the RL controller offers great effectiveness in finding piecewise constant gate-pulse sequences that act on two transmon data qubits coupled by a tunable coupler to generate a controlled-Z (cz) gate with a gate time of 10 ns and an error rate of approximately 4×10-3. Using a gradient-based method to solve the same optimization problem often does not achieve high fidelity for such fast gates. However, we show that using the gate pulses discovered by RL as an ansatz for the gradient-based controller can substantially enhance fidelity compared to using RL alone. While for a 10-ns pulse, this improvement is marginal, the combined RL + gradient approach decreases the gate errors below 10-4 for a gate of length 20 ns.
APA:
Sarma, B., & Hartmann, M. (2025). Designing fast quantum gates using optimal control with a reinforcement-learning ansatz. Physical Review Applied, 23(1). https://doi.org/10.1103/PhysRevApplied.23.014015
MLA:
Sarma, Bijita, and Michael Hartmann. "Designing fast quantum gates using optimal control with a reinforcement-learning ansatz." Physical Review Applied 23.1 (2025).
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