Two-qubit gates in an inductively coupled fluxonium system

In this study, we explore a system of inductively coupled fluxonium qubits, with a focus on minimizing the static ZZ cross-talk and maintaining qubit control. We begin by evaluating the ZZ phase accumulation rate for fluxonium pairs in a multiqubit configuration as well as simulate two-qubit gates using a cross-resonant microwave drive on the control qubit. Even in systems where the ZZ phase accumulation rate remains at a few kHz, the cross-resonant gates show fidelity about 99.9% for gate times under 100 ns. Using various numerical diagonalization techniques, we compare the impact of capacitive and inductive coupling on the nature of the ZZ interactions, demonstrating that inductive coupling is less sensitive to higher-energy transitions. These findings show the potential of inductively coupled fluxonium systems in achieving high-fidelity logical gate operations, as well as possible configurations that aid in the implementation of quantum error correction protocols.