Quantum Error-Correction-Enhanced Magnetometer Overcoming the Limit Imposed by Relaxation

TL;DR

This paper demonstrates a superconducting magnetometer that uses approximate quantum error correction to surpass relaxation-imposed sensitivity limits, enhancing quantum sensing capabilities.

Contribution

It introduces a novel superconducting magnetometry design employing quantum error correction with a tunable coupler to extend coherence time beyond relaxation limits.

Findings

Quantum error correction can extend sensor coherence time.

Superconducting magnetometer surpasses relaxation limits.

Fast correction improves quantum sensing performance.

Abstract

When incorporated in quantum sensing protocols, quantum error correction can be used to correct for high frequency noise, as the correction procedure does not depend on the actual shape of the noise spectrum. As such, it provides a powerful way to complement usual refocusing techniques. Relaxation imposes a fundamental limit on the sensitivity of state of the art quantum sensors which cannot be overcome by dynamical decoupling. The only way to overcome this is to utilize quantum error correcting codes. We present a superconducting magnetometry design that incorporates approximate quantum error correction, in which the signal is generated by a two qubit Hamiltonian term. This two-qubit term is provided by the dynamics of a tunable coupler between two transmon qubits. For fast enough correction, it is possible to lengthen the coherence time of the device beyond the relaxation limit.