# Indistinguishability-enabled coherence for quantum metrology

## TL;DR

This paper demonstrates that quantum indistinguishability of identical particles introduces coherence that can be exploited to enhance quantum metrology, specifically improving phase discrimination accuracy over distinguishable particles.

## Contribution

It reveals that indistinguishability is a source of coherence and shows how it provides an operational advantage in quantum metrology tasks.

## Key findings

- Indistinguishability induces coherence even in independently prepared particles.
- Using indistinguishable particles reduces phase discrimination error.
- Operational advantage demonstrated with a phase discrimination protocol.

## Abstract

Quantum coherence plays a fundamental and operational role in different areas of physics. A resource theory has been developed to characterize the coherence of distinguishable particles systems. Here we show that indistinguishability of identical particles is a source of coherence, even when they are independently prepared. In particular, under spatially local operations, states that are incoherent for distinguishable particles, can be coherent for indistinguishable particles under the same procedure. We present a phase discrimination protocol, in which we demonstrate the operational advantage of using two indistinguishable particles rather than distinguishable ones. The coherence due to the quantum indistinguishability significantly reduces the error probability of guessing the phase using the most general measurements.