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arXiv · 2412.15816

Optimization of Two-Qubit Gates in Tunable-Coupler Architectures Using Single Flux Quantum Control

Boyan Torosov·Bohdan Kulchytskyy·Florian Hopfmueller·John Gunderson·Xiangzhou Kong·Pooya Ronagh
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Abstract

We present a gradient-based method to construct high-fidelity, two-qubit quantum gates in a system consisting of two transmon qubits coupled via a tunable coupler. In particular, we focus on single flux quantum (SFQ) pulses as a promising and scalable alternative to traditional control schemes that use microwave electronics. We develop a continuous embedding scheme to optimize these discrete pulses, taking advantage of auto-differentiation of our model. This approach allows us to achieve fSim-type gates with average gate fidelities on the order of 99.99% and CZ and CNOT gates with fidelities above 99.9%. Furthermore, we provide an alternative semi-analytical construction of these gates via an exact decomposition using a pair of fSim gates which leads to the reduction in memory required to store the associated pulse sequences.

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Boyan Torosov, Bohdan Kulchytskyy, Florian Hopfmueller, John Gunderson, Xiangzhou Kong, Pooya Ronagh. 2024-12-20. Optimization of Two-Qubit Gates in Tunable-Coupler Architectures Using Single Flux Quantum Control. https://arxiv.org/abs/2412.15816

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