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Quantifying the entanglement and coherence of quantum systems is a topic of significant theoretical and practical interest. In this paper, we propose a method to evaluate lower bounds for several widely used coherence measures and genuine…

Quantum Physics · Physics 2025-08-19 Mingyu Liu , Xian Shi

We describe a detector that measures the mutual coherence of two optical fields directly using quantum interference, free from photon noise of the individual irradiances. Our approach utilizes Raman transition in an atomic system where the…

Quantum Physics · Physics 2008-12-16 Jungsang Kim , David J. Brady

Quantum metrology concerns improving the estimation of an unknown parameter using an optimal measurement scheme on the quantum system. More the optimality of the measurement, the better will be the improvement in sensing the value of the…

Quantum Physics · Physics 2025-07-30 H. S. Karthik

The relations between quantum coherence and quantum interference are discussed. A general method for generation of quantum coherence through interference-induced state selection is introduced and then applied to `simple' atomic systems…

Quantum Physics · Physics 2007-05-23 Jean Claude Garreau

Coherence, a strictly quantum phenomenon, has found many applications, from quantum information theory and thermodynamics to quantum foundations and biology. When physical constraints are taken into consideration creation of coherence in a…

Quantum Physics · Physics 2020-04-29 Nikolaos K. Kollas , Kostas Blekos

Quantum entanglement is known as a unique quantum feature that cannot be obtained by classical physics. Over the last several decades, however, such an understanding on quantum entanglement might have confined us in a limited world of weird…

Quantum Physics · Physics 2023-08-01 B. S. Ham

Since quantum coherence is an undoubted characteristic trait of quantum physics, the quantification and application of quantum coherence has been one of the long-standing central topics in quantum information science. Within the framework…

Quantum Physics · Physics 2017-01-04 Yao Yao , G. H. Dong , Li Ge , Mo Li , C. P. Sun

Quantum coherence is a critical resource for many operational tasks. Understanding how to quantify and manipulate it also promises to have applications for a diverse set of problems in theoretical physics. For certain applications, however,…

Quantum Physics · Physics 2016-11-22 Iman Marvian , Robert W. Spekkens

Quantum coherence is a basic feature of quantum physics. Combined with tensor product structure of state space, it gives rise to the novel concepts such as entanglement and quantum correlations, which play a crucial role in quantum…

Quantum Physics · Physics 2017-04-18 Kaifeng Bu , Asutosh Kumar , Lin Zhang , Junde Wu

Quantum coherence, which quantifies the superposition properties of a quantum state, plays an indispensable role in quantum resource theory. A recent theoretical work [Phys. Rev. Lett. \textbf{116}, 070402 (2016)] studied the manipulation…

Quantum Physics · Physics 2017-10-02 Kang-Da Wu , Zhibo Hou , Han-Sen Zhong , Yuan Yuan , Guo-Yong Xiang , Chuan-Feng Li , Guang-Can Guo

We introduce a novel application of the Hartmann sensor, traditionally designed for wavefront sensing, to measure the coherence properties of optical signals. By drawing an analogy between the coherence matrix and the density matrix of a…

Quantum Physics · Physics 2025-04-04 M. Vitek , M. Peterek , D. Koutny , M. Paur , L. Motka , B. Stoklasa , J. Rehacek , Z. Hradil , L. L. Sanchez-Soto

The accumulation of quantum phase in response to a signal is the central mechanism of quantum sensing, as such, loss of phase information presents a fundamental limitation. For this reason approaches to extend quantum coherence in the…

"Quantum sensing" describes the use of a quantum system, quantum properties or quantum phenomena to perform a measurement of a physical quantity. Historical examples of quantum sensors include magnetometers based on superconducting quantum…

Quantum Physics · Physics 2017-08-31 C. L. Degen , F. Reinhard , P. Cappellaro

The concept of bock-coherence, first introduced in [1] and developed in [2,3] encompasses the case where experimental capabilities are not so delicate to perform arbitrary refined measurements on individual atoms. We develop a framework…

Quantum Physics · Physics 2024-02-14 Azam Mani , Fatemeh Rezazadeh , Vahid Karimipour

One of the most important goals in quantum thermodynamics is to demonstrate advantages of thermodynamic protocols over their classical counterparts. For that, it is necessary to (i) develop theoretical tools and experimental set-ups to deal…

Quantum Physics · Physics 2019-05-01 Elisa Bäumer , Matteo Lostaglio , Martí Perarnau-Llobet , Rui Sampaio

Quantum coherence, rooted in the superposition principle of quantum mechanics, is a crucial quantum resource. Various measures, operational interpretations, and generalizations of quantum coherence have been proposed. In recent years, its…

Quantum Physics · Physics 2025-04-22 Hai Wang , Ujjwal Sen

We introduce a reliable compressive procedure to uniquely characterize any given low-rank quantum measurement using a minimal set of probe states that is based solely on data collected from the unknown measurement itself. The procedure is…

Quantum Physics · Physics 2020-11-03 I. Gianani , Y. S. Teo , V. Cimini , H. Jeong , G. Leuchs , M. Barbieri , L. L. Sanchez-Soto

An example of a coherent measurement for the direct evaluation of the degree of polarization of a single-mode optical beam is presented. It is applied to the case of great practical importance where depolarization is caused by polarization…

Quantum Physics · Physics 2015-06-26 N. Gisin

Environment-induced decoherence and superselection have been a subject of intensive research over the past two decades, yet their implications for the foundational problems of quantum mechanics, most notably the quantum measurement problem,…

Quantum Physics · Physics 2008-11-26 Maximilian Schlosshauer

The concept of entanglement fraction is generalized to define coherence fraction of a quantum state. Precisely, it quantifies the proximity of a quantum state to maximally coherent state and it can be used as a measure of coherence.…

Quantum Physics · Physics 2019-06-21 Sumana Karmakar , Ajoy Sen , Indrani Chattopadhyay , Amit Bhar , Debasis Sarkar