Characterize noise correlation and enhance coherence via qubit motion

TL;DR

This paper introduces a new qubit motion method to identify noise correlations in a 7-qubit superconducting system, demonstrating improved coherence times and proposing a sequence to protect quantum states from decoherence.

Contribution

It presents a novel qubit motion technique for efficiently characterizing noise correlations and enhancing qubit coherence in multi-qubit systems.

Findings

Effective noise correlation identification method developed

Qubit motion significantly extends coherence time

Proposed Motion-CPMG sequence improves decoherence protection

Abstract

The identification of spacial noise correlation is of critical importance in developing error-corrected quantum devices, but it has barely been studied so far. In this work, we utilize an effective new method called qubit motion, to efficiently determine the noise correlations between any pair of qubits in a 7-qubit superconducting quantum system. The noise correlations between the same pairs of qubits are also investigated when the qubits are at distinct operating frequencies. What's more, in this multi-qubit system with the presence of noise correlations, we demonstrate the enhancing effect of qubit motion on the coherence of logic qubit, and we propose a Motion-CPMG operation sequence to more efficiently protect the logic state from decoherence, which is experimentally demonstrated to extend the decoherence time of logic qubit by nearly one order of magnitude.