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LIGHT AND COLOR
LIGHT AND COLOR: PHOTONIC RESOURCES FOR QUANTUM METROLOGY
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Pérola MILMAN *, Eloi DESCAMPS, Othmane MESKINE Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Cité, CNRS, UMR 7261 – 10, rue Alice Domon et Leonie Duquet, 750 * perola. milman @ u-paris. fr
https:// doi. org / 10.1051 / photon / 202513148
This is an Open Access article distributed under the terms of the Creative Commons Attribution License( https:// creativecommons. org / licenses / by / 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A finite precision is always associated with the estimation of a parameter, whether it is time, length, or a rotation angle. What does fundamentally limit this precision, given a fixed amount of resources— such as total energy— that are used in parameter estimation? The answer depends on whether classical or quantum strategies are employed. In this paper, we explore the fundamental precision limits of metrological protocols, with a focus on how quantum optics and photonic devices can achieve a quadratic improvement in precision compared to classical setups while using the same amount of resources. We analyze both theoretical aspects and experimental demonstrations, highlighting the respective roles of field statistics and spectral properties in enhancing precision.
BASIC PRINCIPLES OF QUANTUM METROLOGY Precision plays an essential role, not only in technology, but also in our daily life. Optimizing precision is particularly important when it relates to time measurements: time is considered by some as our most precious resource- or the most important parameter. In optical setups, the precision associated with time( or temporal delay) measurements, is often related to the field’ s spectral properties. For instance, for classical monochromatic fields, the time estimation precision limit is roughly said to be the inverse of the field’ s frequency. However, in quantum optics, light is characterized not only by its modal properties- such as spatial or frequency modes- but also by the statistical distribution of photons. This dual nature encapsulates the interplay between the wave-like and particle-like aspects of light. The study of parameter estimation and the associated precision is called metrology. In this contribution, we will discuss how quantum optical strategies can be applied to this field.
We start by recalling the basic principles of metrology, and its quantum counterpart. We will focus throughout this contribution into time estimation precision, but the description provided is valid for other parameters as well. The steps of a parameter estimation protocol are outlined in the pink squares of Box 1, that we will further explore in the context of quantum optics. The first step of the protocol involves generating a quantum state, such as a squeezed state or an entangled multi-photon state— both of which will be
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