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We define the Wigner entropy of a quantum state as the differential Shannon entropy of the Wigner function of the state. This quantity is properly defined only for states that possess a positive Wigner function, which we name…

Quantum Physics · Physics 2022-01-03 Zacharie Van Herstraeten , Nicolas J. Cerf

Significant achievements in the reduction of classical-noise floor will allow macroscopic systems to prepare nearly Heisenberg-Limited quantum states through a continuous measurement, i.e. conditioning. In order to probe the conditional…

Description of nonclassicality of states has hitherto been through violation of Bell inequality and non-separability, with the latter being a stronger constraint. In this paper, we show that this can be further sharpened, by introducing the…

Quantum Physics · Physics 2015-06-18 H. M. Bharath , V. Ravishankar

We propose a new measure of relative incompatibility for a quantum system with respect to two non-commuting observables, and call it quantumness of relative incompatibility. In case of a classical state, order of observation is…

Quantum Physics · Physics 2019-09-30 Manish Kumar Shukla , Rounak Mundra , Arun K Pati , Indranil Chakrabarty , Junde Wu

We present a graphical approach to understanding the degeneracy, density of states, and cumulative state number for some simple quantum systems. By taking advantage of basic computing operations we define a straightforward procedure for…

Quantum Physics · Physics 2014-06-30 Declan Mulhall , Matthew Moelter

In a recent paper, a "distance" function, \cal D, was defined which measures the distance between pure classical and quantum systems. In this work, we present a new definition of a "distance", D, which measures the distance between either…

Quantum Physics · Physics 2009-11-10 Deanna Abernethy , John R. Klauder

Measurement outcomes of a quantum state can be genuinely random (unpredictable) according to the basic laws of quantum mechanics. The Heisenberg-Robertson uncertainty relation puts constrains on the accuracy of two noncommuting observables.…

Quantum Physics · Physics 2017-09-13 Xiao Yuan , Ge Bai , Tianyi Peng , Xiongfeng Ma

The quantum component in uncertainty relation can be naturally characterized by the quantum coherence of a quantum state, which is of paramount importance in quantum information science. Here, we experimentally investigate quantum…

Quantum Physics · Physics 2022-04-25 Lu Liu , Ting Zhang , Xiao Yuan , He Lu

We establish a method of directly measuring and estimating non-classicality - operationally defined in terms of the distinguishability of a given state from one with a positive Wigner function. It allows to certify non-classicality, based…

Quantum Physics · Physics 2011-05-03 A. Mari , K. Kieling , B. Melholt Nielsen , E. S. Polzik , J. Eisert

One of the differences between classical and quantum world is that in the former we can always perform a measurement that gives certain outcomes for all pure states, while such a situation is not possible in the latter. The degree of…

Quantum Physics · Physics 2021-02-02 Anna Szymusiak

We introduce a quantifier of phase-space complexity for discrete-variable (DV) quantum systems. Motivated by a recent framework developed for continuous-variable systems, we construct a complexity measure of quantum states based on the…

Quantum Physics · Physics 2026-03-05 Siting Tang , Shunlong Luo , Matteo G. A. Paris

For one-dimensional continuous-variable quantum systems such as single-mode quantum optical systems, we give a quantification of the quantumness of such a system's state, {\rho}, by introducing the measure of quantumness, {\Xi}, which works…

Quantum Physics · Physics 2026-03-03 Ole Steuernagel , Hsien-Yi Hsieh , Yi-Ru Chen , Ray-Kuang Lee

An extension to computational mechanics complexity measure is proposed in order to tackle quantum states complexity quantification. The method is applicable to any $n-$partite state of qudits through some simple modifications. A Werner…

Computational Physics · Physics 2011-10-28 Yuri Campbell , José Roberto Castilho Piqueira

The nonclassicality of quantum states is a fundamental resource for quantum technologies and quantum information tasks in general. In particular, a pivotal aspect of quantum states lies in their coherence properties, encoded in the…

Quantum Physics · Physics 2024-04-08 Luca Innocenti , Lukas Lachman , Radim Filip

We propose the second moment of the Husimi distribution as a measure of complexity of quantum states. The inverse of this quantity represents the effective volume in phase space occupied by the Husimi distribution, and has a good…

Chaotic Dynamics · Physics 2009-11-07 Ayumu Sugita , Hirokazu Aiba

We initiate an investigation into a notion of state complexity for discrete-variable quantum systems. Specifically, we propose an information-theoretic quantifier for the complexity of quantum states within the stabilizer formalism of…

Quantum Physics · Physics 2026-04-23 Shuangshuang Fu , Shunlong Luo , Yue Zhang

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

A state selected at random from the Hilbert space of a many-body system is overwhelmingly likely to exhibit highly non-classical correlations. For these typical states, half of the environment must be measured by an observer to determine…

Quantum Physics · Physics 2013-03-26 C. Jess Riedel , Wojciech H. Zurek , Michael Zwolak

Quantum computation is a topic of significant recent interest, with practical advances coming from both research and industry. A major challenge in quantum programming is dealing with errors (quantum noise) during execution. Because quantum…

Programming Languages · Computer Science 2018-12-04 Shih-Han Hung , Kesha Hietala , Shaopeng Zhu , Mingsheng Ying , Michael Hicks , Xiaodi Wu

Precise measurements of tiny forces and displacements play an important role in science and technology. The precision of recent experiments, while beginning to reach the limits imposed by quantum mechanics, is necessarily spoiled by the…

Quantum Physics · Physics 2015-06-11 C. L. Latune , B. M. Escher , R. L. de Matos Filho , L. Davidovich