Quantum metrology enhanced by repetitive quantum error correction

TL;DR

This paper demonstrates how repeated quantum error correction can significantly extend the coherence time of a quantum sensor at room temperature, enabling more sensitive detection of magnetic fields beyond natural decoherence limits.

Contribution

It introduces an experimental method to protect a hybrid spin register using repeated quantum error correction, enhancing quantum sensing capabilities at room temperature.

Findings

Extended sensing time beyond natural decoherence limits

Protection against high-frequency noise

Enhanced sensitivity in quantum magnetic field sensing

Abstract

The accumulation of quantum phase in response to a signal is the central mechanism of quantum sensing, as such, loss of phase information presents a fundamental limitation. For this reason approaches to extend quantum coherence in the presence of noise are actively being explored. Here we experimentally protect a room-temperature hybrid spin register against environmental decoherence by performing repeated quantum error correction whilst maintaining sensitivity to signal fields. We use a long-lived nuclear spin to correct multiple phase errors on a sensitive electron spin in diamond and realize magnetic field sensing beyond the timescales set by natural decoherence. The universal extension of sensing time, robust to noise at any frequency, demonstrates the definitive advantage entangled multi-qubit systems provide for quantum sensing and offers an important complement to quantum control techniques. In particular, our work opens the door for detecting minute signals in the presence of high frequency noise, where standard protocols reach their limits.