Suppression of Qubit Crosstalk in a Tunable Coupling Superconducting Circuit

TL;DR

This paper demonstrates a method to suppress qubit crosstalk in superconducting circuits by tuning coupler frequencies for destructive interference, leading to high-fidelity quantum gate operations.

Contribution

It introduces a tunable coupler approach that effectively cancels static ZZ crosstalk in superconducting qubits, improving gate fidelity.

Findings

ZZ crosstalk is suppressed via destructive interference.

Bell state fidelity achieved is 98.5%.

Gate fidelity for $\sqrt{ extrm{iSWAP}}$ is 94.8%.

Abstract

Parasitic crosstalk in superconducting quantum devices is a leading limitation for quantum gates. We demonstrate the suppression of static ZZ crosstalk in a two-qubit, two-coupler superconducting circuit, where the frequency of a tunable coupler can be adjusted such that the ZZ interaction from each coupler destructively interfere. We verify the crosstalk elimination with simultaneous randomized benchmarking, and use a parametrically activated iSWAP interaction to achieve a Bell state preparation fidelity of 98.5% and a $\sqrt{\textrm{iSWAP}}$ gate fidelity of 94.8% obtained via quantum process tomography.