Work

Coherence as a Resource for Phase Estimation

Year: 2026

Type: article

Abstract: Quantum phase estimation is a core task in quantum technologies ranging from metrology to quantum computing, where it appears as a key subroutine in various algorithms. Here, we quantitatively connect the performance of phase estimation protocols with quantum coherence. To achieve this, we construct and characterize resource theories of quantum networks that cannot generate coherence. Given multiple copies of a unitary encoding an unknown phase and access to a fixed coherent state, we estimate the phase using such networks. For a unified and general approach, we assess the quality of the estimate using a generic cost function that penalizes deviations from the true value. We determine the minimal average cost that can be achieved in this manner and explicitly derive optimal protocols. From this, we construct a family of coherence measures that directly connect a state's coherence with its value for phase estimation, demonstrating that every bit of coherence helps. This establishes coherence as a resource that quantifies the performance of phase estimation, and, thus, of any quantum technology relying on it as a subroutine.

Source: Physical Review Letters

DOI: 10.1103/s6d5-lc6g

Authors: Felix Ahnefeld, Thomas Theurer, Martin B. Plenio

Institutions: Universität Ulm, University of Copenhagen

Language: English

Topic: Quantum Information and Cryptography

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,750

Funders: Pacific Institute for the Mathematical Sciences, Danish e-Infrastructure Cooperation, Division of Mathematical Sciences