# Quantum error correction assisted quantum metrology without entanglement

## TL;DR

This paper demonstrates that quantum error correction assisted quantum metrology can achieve noise-free evolution and Heisenberg scaling without entanglement, highlighting the role of quantum resources beyond entanglement.

## Contribution

It reveals that entanglement is not necessary for noise-free quantum metrology in certain QECQM schemes, especially over long and short time scales.

## Key findings

- Entanglement is not required for noise-free evolution in some QECQM problems.
- Noise-free quantum metrology is achievable without quantum correlations over short time scales.
- Long-term noise-free evolution can occur without entanglement in QECQM schemes.

## Abstract

In this article we study the role that quantum resources play in quantum error correction assisted quantum metrology (QECQM) schemes. We show that there exist classes of such problems where entanglement is not necessary to retrieve noise free evolution and Heisenberg scaling in the long time limit. Over short time scales, noise free evolution is also possible even without any form of quantum correlations. In particular, for qubit probes, we show that whenever noise free quantum metrology is possible via QECQM, entanglement free schemes over long time scales and correlation free schemes over short time scales are always possible.