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In this work we investigate the quantum information theoretical limits to several tasks related to lifetime estimation and discrimination of a two-level spontaneous optical emitter. We focus in particular on the model problem of resolving…

Quantum Physics · Physics 2022-06-22 Cheyenne S. Mitchell , Mikael P. Backlund

We describe a quantum limit to measurement of classical spacetimes. Specifically, we formulate a quantum Cramer-Rao lower bound for estimating the single parameter in any one-parameter family of spacetime metrics. We employ the locally…

Quantum Physics · Physics 2017-11-15 T. G. Downes , J. R. van Meter , E. Knill , G. J. Milburn , C. M. Caves

In neutral atom quantum computers, readout and preparation of the atomic qubits are usually based on fluorescence imaging and subsequent analysis of the acquired image. For each atom site, the brightness or some comparable metric is…

Quantum Physics · Physics 2024-09-26 Jonas Winklmann , Andrea Alberti , Martin Schulz

The field of quantum metrology seeks to apply quantum techniques and/or resources to classical sensing approaches with the goal of enhancing the precision in the estimation of a parameter beyond what can be achieved with classical…

We investigate the ultimate precision achievable in Gaussian quantum metrology. We derive general analytical expressions for the quantum Fisher information matrix and for the measurement compatibility condition, ensuring asymptotic…

Quantum Physics · Physics 2018-07-18 Rosanna Nichols , Pietro Liuzzo-Scorpo , Paul A. Knott , Gerardo Adesso

We give a bound to the precision in the estimation of a parameter in terms of the expectation value of an observable. It is an extension of the Cramer-Rao inequality and of the Heisenberg uncertainty relation, where the estimation precision…

Quantum Physics · Physics 2012-07-11 Vittorio Giovannetti , Seth Lloyd , Lorenzo Maccone

In classical optics, there is a well-known resolution limit, called Rayleigh's curse, in the separation of two incoherent optical sources in close proximity. Recently, Tsang et al. revealed that this difficulty may be circumvented in the…

Quantum Physics · Physics 2024-04-30 Masataka Kimizu , Fuyuhiko Tanaka , Akio Fujiwara

The field of quantum sensing explores the use of quantum phenomena to measure a broad range of physical quantities, of both static and time-dependent types. An important figure of merit for sensing time dependent signals is the spectral…

Quantum Physics · Physics 2019-12-05 Tuvia Gefen , Amit Rotem , Alex Retzker

In quantum metrology, it is widely believed that the quantum Cramer-Rao bound is attainable bound while it is not true. In order to clarify this point, we explain why the quantum Cramer-Rao bound cannot be attained geometrically. In this…

Quantum Physics · Physics 2016-06-27 Masahito Hayashi , Sai Vinjanampathy , L. C. Kwek

We determine the quantum Cram\'er-Rao bound for the precision with which the oscillator frequency and damping constant of a damped quantum harmonic oscillator in an arbitrary Gaussian state can be estimated. This goes beyond standard…

Quantum Physics · Physics 2020-08-05 Patrick Binder , Daniel Braun

Precision and accuracy, as two crucial criteria for quantum metrology, have previously lacked rigorous definitions and distinctions. In this paper, we provide a unified definition of precision and accuracy from the perspective of…

Quantum Physics · Physics 2025-07-15 Cong-Gang Song , Qing-yu Cai

We derive a quantum Cram\'er-Rao bound (QCRB) on the error of estimating a time-changing signal. The QCRB provides a fundamental limit to the performance of general quantum sensors, such as gravitational-wave detectors, force sensors, and…

Quantum Physics · Physics 2011-10-31 Mankei Tsang , Howard M. Wiseman , Carlton M. Caves

Enhancing the precision of a measurement requires maximizing the information that can be gained about the quantity of interest from probing a system. For optical based measurements, such an enhancement can be achieved through two…

Accurate quantitative mapping of gamma-ray sources is critical for applications ranging from radiological emergency response and environmental monitoring to nuclear security and deep space exploration. Here, we show that integrating…

Instrumentation and Detectors · Physics 2026-02-03 David Breitenmoser , Alberto Stabilini , Malgorzata Magdalena Kasprzak , Sabine Mayer

To quantify quantum optical coherence requires both the particle- and wave-natures of light. For an ideal laser beam [1,2,3], it can be thought of roughly as the number of photons emitted consecutively into the beam with the same phase.…

Quantum Physics · Physics 2020-11-06 Travis J. Baker , S. N. Saadatmand , Dominic W. Berry , Howard M. Wiseman

Quantum sensors hold considerable promise for precision measurement, yet their capabilities are inherently constrained by environmental noise. A fundamental task in quantum sensing is determining the precision limit of noisy sensor devices.…

Quantum Physics · Physics 2026-04-14 Dayou Yang , Moulik Ketkar , Koenraad Audenaert , Susana F. Huelga , Martin B. Plenio

The problem of measuring a time-varying phase, even when the statistics of the variation is known, is considerably harder than that of measuring a constant phase. In particular, the usual bounds on accuracy - such as the $1/(4\bar{n})$…

Quantum Physics · Physics 2018-05-01 Kiarn T. Laverick , Howard M. Wiseman , Hossien T. Dinani , Dominic W. Berry

Many results in the quantum metrology literature use the Cram\'er-Rao bound and the Fisher information to compare different quantum estimation strategies. However, there are several assumptions that go into the construction of these tools,…

Quantum Physics · Physics 2018-01-31 Jesús Rubio , Paul Knott , Jacob Dunningham

A longstanding problem in quantum metrology is how to extract as much information as possible in realistic scenarios with not only multiple unknown parameters, but also limited measurement data and some degree of prior information. Here we…

Quantum Physics · Physics 2020-03-24 Jesús Rubio , Jacob Dunningham

We develop a theoretical framework for the analysis of the quantum coherence of light emitted by two independent single-photon sources in an arbitrary environment. The theory provides design rules for the control of the degree of quantum…

Quantum Physics · Physics 2016-03-30 Antoine Canaguier-Durand , Rémi Carminati