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We introduce an experimentally accessible method to measure a unique degree of nonclassicality, based on the quantum superposition principle, for arbitrary quantum states. We formulate witnesses and test a given state for any particular…

Quantum Physics · Physics 2014-09-19 M. Mraz , J. Sperling , W. Vogel , B. Hage

We identify a new universality class in one-dimensional driven open quantum systems with a dark state. Salient features are the persistence of both the microscopic non-equilibrium conditions as well as the quantum coherence of dynamics…

Quantum Gases · Physics 2016-02-24 Jamir Marino , Sebastian Diehl

We study some discrete symmetries of unbiased (Hadamard) and biased quantum walk on a line, which are shown to hold even when the quantum walker is subjected to environmental effects. The noise models considered in order to account for…

Quantum Physics · Physics 2009-11-13 C. M. Chandrashekar , R. Srikanth , Subhashish Banerjee

The study of measurements in quantum mechanics exposes many of the ways in which the quantum world is different. For example, one of the hallmarks of quantum mechanics is that observables may be incompatible, implying among other things…

Quantum Physics · Physics 2025-10-15 Emery Doucet , Sebastian Deffner

We present a method for the experimental measurement of nonclassicality witnesses and demonstrate its application. Our proposal only requires the coherent displacement of the initial state, which can be achieved by overlapping the latter…

Quantum Physics · Physics 2015-06-05 T. Kiesel , W. Vogel

We investigate the genuinely quantum features of continuous-time quantum walks by combining a single-time and a multi-time quantifier of nonclassicality. On the one hand, we consider the quantum-classical dynamical distance…

Quantum Physics · Physics 2026-04-15 Paolo Luppi , Claudia Benedetti , Andrea Smirne

The origin of non-classical correlations is difficult to identify since the uncertainty principle requires that information obtained about one observable invariably results in the disturbance of any other non-commuting observable. Here,…

Quantum Physics · Physics 2014-07-01 Holger F. Hofmann

We provide an overview of a canonical formalism that describes mixed quantum-classical systems in terms of statistical ensembles on configuration space, and discuss applications to measurement theory. It is shown that the formalism allows a…

Quantum Physics · Physics 2009-07-06 M Reginatto , M J W Hall

A symmetric measure of quantum correlation based on the Hilbert-Schmidt distance is presented in this paper. For two-qubit states, we simplify considerably the optimization procedure so that numerical evaluation can be performed…

Quantum Physics · Physics 2011-07-18 Mingjun Shi , Fengjian Jiang , Jiangfeng Du

We study the motion of two non-interacting quantum particles performing a random walk on a line and analyze the probability that the two particles are detected at a particular position after a certain number of steps (meeting problem). The…

Quantum Physics · Physics 2007-05-23 M. Stefanak , T. Kiss , I. Jex , B. Mohring

Quantum theory has the intriguing feature that is inconsistent with noncontextual hidden variable models, for which the outcome of a measurement does not depend on which other compatible measurements are being performed concurrently. While…

Quantum Physics · Physics 2015-08-20 Hong-Yi Su , Jing-Ling Chen , Yeong-Cherng Liang

A central feature of quantum mechanics is the non-commutativity of operators used to describe physical observables. In this article, we present a critical analysis on the role of non-commutativity in quantum theory, focusing on its…

Quantum Physics · Physics 2018-03-20 Luca Curcuraci

Quantum coherence is one of the primary non-classical features of quantum systems. While protocols such as the Leggett-Garg inequality (LGI) and quantum tomography can be used to test for the existence of quantum coherence and dynamics in a…

Quantum Physics · Physics 2012-12-04 Che-Ming Li , Neill Lambert , Yueh-Nan Chen , Guang-Yin Chen , Franco Nori

A classical state-preparation device cannot generate states in relative superposition. We introduce classical models in which devices that are individually unable to generate states with relative superposition can be stochastically…

Quantum Physics · Physics 2026-02-03 Gabriele Cobucci , Alexander Bernal , Martin J. Renner , Armin Tavakoli

A non-commuting measurement transfers, via the apparatus, information encoded in a system's state to the external "observer". Classical measurements determine properties of physical objects. In the quantum realm, the very same notion…

Quantum Physics · Physics 2016-08-31 Bartłomiej Gardas , Sebastian Deffner , Avadh Saxena

The state disturbance induced by locally measuring a quantum system yields a signature of nonclassical correlations beyond entanglement. Here we present a detailed study of such correlations for two-qubit mixed states. To overcome the…

Quantum Physics · Physics 2011-08-22 Davide Girolami , Mauro Paternostro , Gerardo Adesso

More than a century after the inception of quantum theory, the question of which traits and phenomena are fundamentally quantum remains under debate. Here we give an answer to this question for temporal processes which are probed…

Quantum walks are dynamic systems with a wide range of applications in quantum computation and quantum simulation of analog systems, therefore it is of common interest to understand what changes from an isolated process to one embedded in…

Quantum Physics · Physics 2022-12-19 Luísa Toledo Tude , Marcos C. de Oliveira

In this work we propose a measure for the quantum discord of indistinguishable particles, based on the definition of entanglement of particles given in [H. M. Wiseman et al., Phis. Rev. Lett 91, 097902 (2003)]. This discord of particles is…

Quantum Physics · Physics 2016-04-28 Andrea Beggi , Fabrizio Buscemi , Paolo Bordone

It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical…

Quantum Physics · Physics 2016-04-08 Keisuke Fujii , Shuhei Tamate