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Coherence as a Resource for Phase Estimation
Felix Ahnefeld1, Thomas Theurer2, Martin B Plenio1
1Universität Ulm, Institute of Theoretical Physics, Albert-Einstein-Allee 11, D-89069 Ulm, Germany.
Physical Review Letters
|May 22, 2026
Summary
This study quantifies how quantum coherence enhances quantum phase estimation. Researchers developed resource theories to show that every bit of coherence directly improves phase estimation performance in quantum technologies.
Area of Science:
- Quantum Information Science
- Quantum Metrology
- Quantum Computing
Background:
- Quantum phase estimation is fundamental to quantum technologies like metrology and computing.
- Its performance is often limited by practical constraints, necessitating a deeper understanding of resource requirements.
Purpose of the Study:
- To quantitatively link the performance of quantum phase estimation protocols with quantum coherence.
- To establish coherence as a quantifiable resource for phase estimation accuracy.
Main Methods:
- Construction and characterization of resource theories for quantum networks incapable of generating coherence.
- Phase estimation using multiple copies of a unitary phase-encoding operation and a fixed coherent state.
- Assessment of estimation quality using a generic cost function penalizing deviations from the true phase value.
Main Results:
- Determination of the minimal average cost achievable for phase estimation under coherence constraints.
- Derivation of optimal phase estimation protocols.
- Construction of new coherence measures directly correlating coherence with phase estimation value, proving 'every bit of coherence helps'.
Conclusions:
- Quantum coherence is a critical resource that directly quantifies the performance of quantum phase estimation.
- This finding has broad implications for any quantum technology utilizing phase estimation as a subroutine.
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