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We introduce the concept of degree of quantumness in quantum synchronization, a measure of the quantum nature of synchronization in quantum systems. Following techniques from quantum information, we propose the number of non-commuting…

Quantum Physics · Physics 2020-01-06 H. Eneriz , D. Z. Rossatto , F. A. Cárdenas-L'opez , E. Solano , M. Sanz

The effects of the measurement apparatus on quantum coherence are studied by considering a purely dephasing model of a qubit. The initial state is prepared from a thermal state of the whole system by performing a nonselective measurement on…

Quantum Physics · Physics 2021-12-22 Filippo Giraldi

It is not possible to obtain information about the observable properties of a quantum system without a physical interaction between the system and an external meter. This physical interaction is described by a unitary transformation of the…

Quantum Physics · Physics 2021-07-29 Tomonori Matsushita , Holger F. Hofmann

The concept of compatibility originally emerged as a synonym for the commutativity of observables and later evolved into the notion of measurement compatibility. In any case, however, it has remained predominantly algebraic in nature, tied…

Quantum Physics · Physics 2026-03-09 Mariana Storrer , Patrick Lima , Ana C. S. Costa , Sebastião Pádua , Renato M. Angelo

Certifying maximal quantum randomness without assumptions about system dimension remains a pivotal challenge for secure communication and foundational studies. Here, we introduce a generalized framework to directly certify maximal…

Quantum Physics · Physics 2025-07-15 Tianqi Zheng , Yi Li , Yu Xiang , Qiongyi He

Quantum instruments describe outcome probability as well as state change induced by measurement of a quantum system. Incompatibility of two instruments, i. e. the impossibility to realize them simultaneously on a given quantum system,…

Quantum Physics · Physics 2024-02-14 Leevi Leppäjärvi , Michal Sedlák

Quantum machine learning models have the potential to offer speedups and better predictive accuracy compared to their classical counterparts. However, these quantum algorithms, like their classical counterparts, have been shown to also be…

Quantum Physics · Physics 2021-05-27 Maurice Weber , Nana Liu , Bo Li , Ce Zhang , Zhikuan Zhao

By invoking quantum estimation theory we formulate bounds of errors in quantum measurement for arbitrary quantum states and observables in a finite-dimensional Hilbert space. We prove that the measurement errors of two observables satisfy…

Quantum Physics · Physics 2013-05-29 Yu Watanabe , Takahiro Sagawa , Masahito Ueda

Information-theoretic definitions for the noise associated with a quantum measurement and the corresponding disturbance to the state of the system have recently been introduced [F. Buscemi et al., Phys. Rev. Lett. 112, 050401 (2014)]. These…

Quantum Physics · Physics 2016-12-14 Alastair A. Abbott , Cyril Branciard

Relevance of key quantum information measures for analysis of quantum systems is discussed. It is argued that possible ways of measuring quantum information are based on compatibility/incompatibility of the quantum states of a quantum…

Quantum Physics · Physics 2015-06-26 B. A. Grishanin , V. N. Zadkov

Complementarity restricts the accuracy with which incompatible quantum observables can be jointly measured. Despite popular conception, the Heisenberg uncertainty relation does not quantify this principle. We report the experimental…

Measurement incompatibility is one of the cornerstones of quantum theory. This phenomenon appears in many forms, of which the concept of non-joint measurability has received considerable attention in the recent years. In order to…

Quantum Physics · Physics 2023-04-05 Juha-Pekka Pellonpää , Sébastien Designolle , Roope Uola

Quantum theory is inconsistent with any local hidden variable model as was first shown by Bell. To test Bell inequalities two separated observers extract correlations from a common ensemble of identical systems. Since quantum theory does…

Quantum Physics · Physics 2011-01-19 Shmuel Marcovitch , Benni Reznik

The so-called measurement problem of quantum theory (QT) is still lacking a satisfactory, or at least widely agreed upon, solution. A number of theories, known as interpretations of quantum theory, have been proposed and found differing…

Quantum Physics · Physics 2016-11-26 Hans H. Diel

Uncertainty principle is one of the fundamental principles of quantum mechanics. In this work, we derive two uncertainty equalities, which hold for all pairs of incompatible observables. We also obtain an uncertainty relation in weak…

Quantum Physics · Physics 2015-05-12 Qiu-Cheng Song , Cong-Feng Qiao

One of the formulations of Heisenberg uncertainty principle, concerning so-called measurement uncertainty, states that the measurement of one observable modifies the statistics of the other. Here, we derive such a measurement uncertainty…

A quantitative measure of quantum coherence was recently introduced, in the context of quantum information theory. This measure has also been propounded as a good quantifier of the wave nature of quantum objects. However, actually measuring…

Quantum Physics · Physics 2017-04-12 Tania Paul , Tabish Qureshi

Quantum metrology based on quantum entanglement and quantum coherence improves the accuracy of measurement. In this paper, we briefly review the schemes of quantum metrology in various complex systems, including non-Markovian noise,…

Quantum Physics · Physics 2024-01-18 Qing Ai , Yang-Yang Wang , Jing Qiu

Simultaneous estimation of multiple parameters in quantum metrological models is complicated by factors relating to the (i) existence of a single probe state allowing for optimal sensitivity for all parameters of interest, (ii) existence of…

Quantum Physics · Physics 2019-02-01 Sammy Ragy , Marcin Jarzyna , Rafal Demkowicz-Dobrzanski

One unique feature of quantum mechanics is the Heisenberg uncertainty principle, which states that the outcomes of two incompatible measurements cannot simultaneously achieve arbitrary precision. In an information-theoretic context of…

Quantum Physics · Physics 2017-11-08 Jian Xing , Yu-Ran Zhang , Shang Liu , Yan-Chun Chang , Jie-Dong Yue , Heng Fan , Xin-Yu Pan