Characterization of simultaneous 2-qubit parametric gate operations on a 25-qubit processor

Measuring crosstalk is crucial for enhancing the reliability, scalability, and performance of quantum processors. We characterize the magnetic-flux crosstalk during simultaneous two-qubit gate operations on a 25-qubit device in flip-chip architecture [1]. Our processor consists of fixed-frequency transmon qubits and tunable-transmon nearest-neighbor couplers placed on a square grid. The frequencies of the qubits and couplers are allocated in two groups in a repeating pattern, to mitigate frequency collisions and to be scalable to large device sizes [2]. The two-qubit CZ gates are driven with DC and AC flux signals by parametric modulation of the coupler flux. We characterize the coupler flux crosstalk by comparing gate fidelities of individual and simultaneous interleaved randomized benchmarking sequences.

[1] Kosen et al. PRXQ 5, 030350 (2024). [2] Osman et al. PRR 5, 043001 (2023).