Control and mitigation of microwave crosstalk effect with superconducting qubits

TL;DR

This paper presents a scheme to mitigate microwave crosstalk errors in superconducting qubits, enhancing gate fidelity without increasing circuit complexity, crucial for scalable quantum computing.

Contribution

The authors propose a novel error mitigation method that controls detuning, decomposes gates, and optimizes virtual Z gates to reduce crosstalk errors without extra signals or circuit depth increase.

Findings

Crosstalk errors can be constrained within the computational subspace.

Simultaneous single-qubit gate fidelities improve significantly.

No additional compensation signals or circuit depth increase are needed.

Abstract

Improving gate performance is vital for scalable quantum computing. The universal quantum computing also requires the gate fidelity to reach a high level. For superconducting quantum processor, which operates in the microwave band, the single-qubit gates are usually realized with microwave driving. The crosstalk between microwave pulses is a non-negligible error source. In this article, we propose an error mitigation scheme to address this crosstalk issue for single-qubit gates. There are three steps in our method. First, by controlling the detuning between qubits, the microwave induced classical crosstalk error can be constrained within the computational subspace. Second, by applying the general decomposition procedure, arbitrary single-qubit gate can be decomposed as a sequence of $\sqrt{X}$ and virtual Z gates. Finally, by optimizing the parameters in virtual Z gates, the error constrained in the computational space can be corrected. Using our method, no additional compensation signals are needed, arbitrary single-qubit gate time will not be prolonged, and the circuit depth containing simultaneous single-qubit gates will also not increase. The simulation results show that, in specific regime of qubit-qubit detuning, the infidelities of simultaneous single-qubit gates can be as low as which without microwave crosstalk.