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We introduce the notion of compatibility dimension for a set of quantum measurements: it is the largest dimension of a Hilbert space on which the given measurements are compatible. In the Schr\"odinger picture, this notion corresponds to…

Quantum Physics · Physics 2022-10-26 Faedi Loulidi , Ion Nechita

The topic of measurement in relativistic quantum field theory is addressed in this article. Some of the long standing problems of this subject are highlighted, including the incompatibility of an instantaneous ``collapse of the…

Mathematical Physics · Physics 2024-11-21 Christopher J. Fewster , Rainer Verch

If a quantum experiment includes random processes, then the results of repeated measurements can appear consistent with irreversible decoherence even if the system's evolution prior to measurement was reversible and unitary. Two thought…

Quantum Physics · Physics 2012-06-01 Sam Kennerly

It is proposed a possible new approach of quantum measurements (QMS), disconnected of the traditional interpretation of uncertainty relations and independent of any appeal to the strange idea of collapse (reduction) of wave functions. The…

Quantum Physics · Physics 2007-05-23 S. Dumitru

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology and cryptography. Yet, there is no universally efficient method for quantifying coherence either in…

Quantum Physics · Physics 2014-10-24 Davide Girolami

We consider the problem of discriminating between states of a specified set with maximum confidence. For a set of linearly independent states unambiguous discrimination is possible if we allow for the possibility of an inconclusive result.…

Quantum Physics · Physics 2007-05-23 Sarah Croke , Erika Andersson , Stephen M. Barnett , Claire R. Gilson , John Jeffers

We consider the motion of a quantum particle whose position is measured in random places at random moments in time. We contrast this motion with the motion of a quantum particle in a potential which varies randomly in space and in time,…

Disordered Systems and Neural Networks · Physics 2025-07-10 Victor Gurarie

Maximum likelihood principle is shown to be the best measure for relating the experimental data with the predictions of quantum theory.

Quantum Physics · Physics 2009-10-31 Z. Hradil , J. Summhammer

In quantum theory, it is known for a pair of noncommutative observables that there is no state on which they take simultaneously definite values, and that there is no joint measurement of them. They are called preparation uncertainty and…

Quantum Physics · Physics 2020-09-02 Ryo Takakura , Takayuki Miyadera

Standard procedures for entanglement detection assume that experimenters can exactly implement specific quantum measurements. Here, we depart from such idealizations and investigate, in both theory and experiment, the detection of genuine…

Quantum Physics · Physics 2024-10-10 Huan Cao , Simon Morelli , Lee A. Rozema , Chao Zhang , Armin Tavakoli , Philip Walther

Coherent superpositions are one of the hallmarks of quantum mechanics and are vital for any quantum mechanical device to outperform the classically achievable. Generically, superpositions are verified in interference experiments, but…

Quantum Physics · Physics 2020-03-04 Benjamin Dive , Nikolaos Koukoulekidis , Stefanos Mousafeiris , Florian Mintert

Measurements in quantum theory can fail to be jointly measurable. Like entanglement, this incompatibility of measurements is necessary but not sufficient for violating Bell inequalities. The (in)compatibility relations among a set of…

Quantum Physics · Physics 2024-11-21 Shiv Akshar Yadavalli , Nikola Andrejic , Ravi Kunjwal

We suggest generalized robustness for quantifying nonlocality and derive its equivalence to the maximum violation ratio of Bell inequalities defined as vectors with non-negative elements. We investigate its properties by comparing it with…

Quantum Physics · Physics 2025-04-29 Kyunghyun Baek , Junghee Ryu , Jinhyoung Lee

Joint measurements of non-commuting observables are characterized by unavoidable measurement uncertainties that can be described in terms of the error statistics for input states with well-defined values for the target observables. However,…

Quantum Physics · Physics 2015-10-28 Shota Kino , Taiki Nii , Holger F. Hofmann

A probabilistic propositional logic, endowed with an epistemic component for asserting (non-)compatibility of diagonizable and bounded observables, is presented and illustrated for reasoning about the random results of projective…

Logic · Mathematics 2018-03-20 A. Sernadas , J. Rasga , C. Sernadas , L. Alcácer , A. B. Henriques

We consider the group testing problem, in which one seeks to identify a subset of defective items within a larger set of items based on a number of noisy tests. While matching achievability and converse bounds are known in several cases of…

Information Theory · Computer Science 2016-04-05 Jonathan Scarlett , Volkan Cevher

We propose a protocol to test whether the postulate of a measurement acting as an instantaneous projection onto an eigenstate of the measurement apparatus is compatible with physical reality. This approach is solely based on repeated…

Quantum Physics · Physics 2025-06-26 Leonard Werner Pingen , Mattia Moroder , Sebastian Paeckel

We prove uncertainty relations that quantitatively express the impossibility of jointly sharp preparation of pre- and post-selected quantum states for measuring incompatible observables during the weak measurement. By defining a suitable…

Quantum Physics · Physics 2014-11-27 Arun Kumar Pati , Junde Wu

Standard projective measurements represent a subset of all possible measurements in quantum physics, defined by positive-operator-valued measures. We study what quantum measurements are projective simulable, that is, can be simulated by…

Quantum Physics · Physics 2017-11-15 Michał Oszmaniec , Leonardo Guerini , Peter Wittek , Antonio Acín

The question whether quantum measurements reflect some underlying objective reality has no generally accepted answer. We show that description of such reality is possible under natural conditions such as linearity and causality, although in…

Quantum Physics · Physics 2015-09-15 Adam Bednorz