Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Frontiers in Optics

Quantum-limited Loss and Phase Estimation Using All-pass Ring Resonators

Alexandre Belsley, Euan J. Allen, Animesh Datta, Jonathan C. F. Matthews

Published Jan 1, 2022• 0 citations
Publisher

Abstract

We derive the fundamental quantum limits in estimating the absorption coefficient and refractive index of an analyte using all-pass ring resonators. We find coherent-states are optimal probes and can outperform any quantum probe single-pass strategy.
DOI
10.1364/fio.2022.jw4a.26

Related papers

Quantum-limited absorption estimation with ring resonators

Alexandre Belsley, Euan J. Allen, Animesh Datta +1 more

Coherent-state probes in appropriately designed all-pass ring resonators outperform any quantum probe single-pass absorption estimation strategy, including those using Fock or bright squeezed states.

Optical Sensors and Sensing Congress•Jan 1, 2022•0 citations

Advantage of Coherent States in Ring Resonators over Any Quantum Probe Single-Pass Absorption Estimation Strategy

Alexandre Belsley, Euan J. Allen, Animesh Datta +1 more

Quantum states of light have been shown to enhance precision in absorption estimation over classical strategies. By exploiting interference and resonant enhancement effects, we show that coherent-state probes in all-pass ring resonators can outperform any quantum probe single-pass strategy even when normalized by the mean input photon number. We also find that under optimal conditions coherent-state probes equal the performance of arbitrarily bright pure single-mode squeezed probes in all-pass ring resonators.

arXiv:2112.07557•Physical Review Letters•Jun 6, 2022•21 citations

Coherent States in Ring Resonators Outperform Any Quantum Probe Single-pass Absorption Estimation Strategy

Alexandre Belsley, Euan J. Allen, Animesh Datta +1 more

By leveraging interference and resonance enhancement effects, we find all-pass ring resonators with coherent-state probes can estimate absorption more precisely than any quantum probe single-pass strategy, including those using squeezed or Fock states.

Quantum 2.0 Conference and Exhibition•Jan 1, 2022•0 citations

Surpassing the Quantum Limit in Bosonic Loss Estimation without Quantum Probes

Yu Tao, Xinhang Li, Lang Li +5 more

Bosonic loss estimation has an important role in quantum metrology. It was once believed that the ultimate precision of this task is restricted to the standard quantum limit if no quantum probe is involved. Nevertheless, a recent proposal showed that this limit can be surpassed by utilizing ring resonators with coherent state probe. Here, we experimentally realize the resonator-based bosonic loss estimation and verify the resonant enhancement effect. This Letter explores the advantages of resonator-based metrology and sheds light on the development of high-precision miniature sensors.

Physical Review Letters•Aug 6, 2024•3 citations

Limits for molecular spectroscopy from quantum channel discrimination

Anirban Dey, Akib Karim, Pieter Kok +2 more

Absorption spectroscopy identifies molecules by detecting frequency-dependent optical loss, and its fundamental limit is a quantum channel-discrimination problem. In this work, we develop a general framework for characterizing the ultimate quantum limit of molecular absorption spectroscopy without collective measurements: we formulate it as an asymmetric quantum hypothesis testing task between different absorption channels. Using a semidefinite-programming formulation, we construct optimal probe states and compare them with coherent-state photon counting, Fock states, and two-mode squeezed vacuum probes. We introduce a random-loss channel model for imperfectly known background transmission, reflecting the fact that a blank experiment need not return all incident photons due to scattering, solvent absorption, or collection losses. Our results show that optimized non-classical probes can substantially outperform conventional laser spectroscopy, and that the advantage is robust to realistic baseline random loss. % In multi-frequency spectroscopy, the optimization also determines how photons should be allocated across absorption lines, revealing an additional resource-allocation advantage beyond single-mode state engineering. We illustrate our framework using infrared detection of 4-nitrophenol against chemically relevant comparison molecules, showing how quantum channel-discrimination methods provide constructive performance limits for molecular spectroscopy under realistic photon constraints.

quant-pharXiv:2609.27344•Sep 24, 2026•0 citations

Quantum enhanced estimation of optical detector efficiencies

Marco Barbieri, Datta Animesh, Tim J. Bartley +3 more

Abstract Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by identifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimating the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter using Fisher information as a benchmark. We provide theoretical results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies, when using Fock states and coherent states as probes.

arXiv:1502.00681•Quantum Measurements and Quantum Metrology•Jan 1, 2016•2 citations
Quantum states of light have been shown to enhance precision in absorption estimation over classical strategies. By exploiting interference and resonant enhancement effects, we show that coherent-state probes in all-pass ring resonators can outperform any quantum probe single-pass strategy even when normalized by the mean input photon number. We also find that under optimal conditions coherent-state probes equal the performance of arbitrarily bright pure single-mode squeezed probes in all-pass ring resonators.
Bosonic loss estimation has an important role in quantum metrology. It was once believed that the ultimate precision of this task is restricted to the standard quantum limit if no quantum probe is involved. Nevertheless, a recent proposal showed that this limit can be surpassed by utilizing ring resonators with coherent state probe. Here, we experimentally realize the resonator-based bosonic loss estimation and verify the resonant enhancement effect. This Letter explores the advantages of resonator-based metrology and sheds light on the development of high-precision miniature sensors.
Absorption spectroscopy identifies molecules by detecting frequency-dependent optical loss, and its fundamental limit is a quantum channel-discrimination problem. In this work, we develop a general framework for characterizing the ultimate quantum limit of molecular absorption spectroscopy without collective measurements: we formulate it as an asymmetric quantum hypothesis testing task between different absorption channels. Using a semidefinite-programming formulation, we construct optimal probe states and compare them with coherent-state photon counting, Fock states, and two-mode squeezed vacuum probes. We introduce a random-loss channel model for imperfectly known background transmission, reflecting the fact that a blank experiment need not return all incident photons due to scattering, solvent absorption, or collection losses. Our results show that optimized non-classical probes can substantially outperform conventional laser spectroscopy, and that the advantage is robust to realistic baseline random loss. % In multi-frequency spectroscopy, the optimization also determines how photons should be allocated across absorption lines, revealing an additional resource-allocation advantage beyond single-mode state engineering. We illustrate our framework using infrared detection of 4-nitrophenol against chemically relevant comparison molecules, showing how quantum channel-discrimination methods provide constructive performance limits for molecular spectroscopy under realistic photon constraints.
Abstract Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by identifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimating the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter using Fisher information as a benchmark. We provide theoretical results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies, when using Fock states and coherent states as probes.