Reviving the precision of multiple entangled probes in an open system by simple $\pi$-pulse sequences

TL;DR

This paper demonstrates that simple $$-pulse sequences can significantly restore the measurement precision of entangled quantum probes in noisy environments, enhancing quantum metrology's robustness.

Contribution

It introduces a universal dynamical decoupling protocol using $$-pulses to revive quantum metrology precision under various noise conditions.

Findings

Revived measurement precision scaling as N^{-k} with k between 5/6 and 11/12.

Performance depends on noise spectrum, controllable for further improvement.

Protocol effective for pure dephasing and relaxation noise in entangled systems.

Abstract

Quantum metrology with entangled states in realistic noisy environments always suffers from decoherence. Therefore, the measurement precision is greatly reduced. Here we applied the dynamical decoupling method to protect the $N$-qubit quantum metrology protocol and successfully revived the scaling of the measurement precision as ${N^{-k}}$ with $k\in \left[{5/6,11/12}\right]$. The degree of the precision revival, as determined by the noise spectrum distribution, indicates that the performance of the protected protocol can be further improved by controlling the noise spectrum. Such a protected protocol is proved to be universal for entanglement-based quantum metrology in the pure dephasing and relaxation noise, which should stimulate the development of practical quantum metrology for weak signal detection of microscopic physics.