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

2024/12/20 by Boyan T. Torosov, Torosov, Boyan, Bohdan Kulchytskyy +9
Computer Science · #FOS: Physical sciences #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Physics (quant-ph) #Quantum-Dot Cellular Automata

paper · pdf · doi:10.48550/arxiv.2412.15816

openalex publication_date 2024/12/20 · openalex created_date 2024/12/24 · openalex updated_date 2026/07/28

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.

Related

• High-fidelity two-qubit gates with transmon qubits using bipolar flux pulses and tunable couplers
• Optimization of High-Fidelity Single-Qubit Gates for Fluxoniums Using Single-Flux Quantum Control
• High-fidelity √(iSWAP) gates using a fixed coupler driven by two microwave pulses
• Fast microwave-driven two-qubit gates between fluxonium qubits with a transmon coupler
• Co-designing Transmon devices for control with simple pulses