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Given two observables $A$ and $B$, one can associate to every quantum state a Kirkwood-Dirac (KD) quasiprobability distribution. KD distributions are like joint classical probabilities except that they can have negative or nonreal values,…

Quantum Physics · Physics 2025-06-30 Christopher Langrenez , Stephan De Bièvre , David R. M. Arvidsson-Shukur

We determine the Kirkwood-Dirac quasiprobability (KDQ) distribution associated to the stochastic instances of internal energy variations for the quantum system and environment particles in coherent Markovian collision models. In the case…

Quantum Physics · Physics 2025-07-23 Marco Pezzutto , Gabriele De Chiara , Stefano Gherardini

Temporal quantum states generalize the multipartite density operator formalism to the time domain, enabling a unified treatment of quantum systems with both timelike and spacelike correlations. Despite a growing body of temporal state…

Quantum Physics · Physics 2026-01-12 Zhian Jia , Kavan Modi , Dagomir Kaszlikowski

A quantum thermodynamic system can conserve non-commuting observables, but the consequences of this phenomenon on relaxation are still not fully understood. We investigate this problem by leveraging an observable-dependent approach to…

We investigate features of the quasi-joint-probability distribution for finite-state quantum systems, especially the two-state and three-state quantum systems, comparing different types of quasi-joint-probability distributions based on the…

Quantum Physics · Physics 2024-04-01 Shun Umekawa , Jaeha Lee , Naomichi Hatano

The question of when the Kirkwood-Dirac quasiprobability serves as the most appropriate description for quantum measurements has remained unresolved, particularly across different measurement strengths. While known to generate anomalous…

Quantum Physics · Physics 2026-01-27 Bo Zhang , Yusuf Turek

Kirkwood-Dirac representations of quantum states are increasingly finding use in many areas within quantum theory. Usually, representations of this sort are only applied to provide a representation of quantum states (as complex functions…

Quantum Physics · Physics 2025-08-15 David Schmid , Roberto D. Baldijão , Yìlè Yīng , Rafael Wagner , John H. Selby

We present a new measure of non-Markovianity based on the property of nonincreasing quantum coherence via Kirkwood-Dirac (KD) quasiprobability under incoherent completely positive trace-preserving maps. Quantum coherence via the KD…

Quantum Physics · Physics 2025-06-30 Yassine Dakir , Abdallah Slaoui , Rachid Ahl Laamara

We address the problem of identifying non-Markovian quantum time evolutions of an open quantum system by only performing measurements of the system's energy. We demonstrate that violations of CP-divisibility are always witnessed by…

Quantum Physics · Physics 2026-05-27 Marco Pezzutto , Anton Corr , Gabriele De Chiara , Salvatore Lorenzo , Stefano Gherardini

In quadratic fermionic models we determine a quantum correction to the work statistics after a sudden and a time-dependent driving. Such a correction lies in the non-commutativity of the initial quantum state and the time-dependent…

Quantum Physics · Physics 2023-09-12 Alessandro Santini , Andrea Solfanelli , Stefano Gherardini , Mario Collura

Among the many quasiprobability representations of quantum mechanics, the family of Kirkwood-Dirac (KD) representations has come to the foreground in recent years. Each such KD representation is determined by the choice of two complementary…

Quantum Physics · Physics 2026-05-29 Matéo Spriet , Christopher Langrenez , Raymond Brummelhuis , Stephan De Bièvre

In 1945, Dirac attempted to develop a "formal probability" distribution to describe quantum operators in terms of two non-commuting variables, such as position x and momentum p [Rev. Mod. Phys. 17, 195 (1945)]. The resulting…

Quantum Physics · Physics 2014-03-06 Jeff S. Lundeen , Charles Bamber

We provide an in-depth study of the recently introduced notion of completely incompatible observables and its links to the support uncertainty and to the Kirkwood-Dirac nonclassicality of pure quantum states. The latter notion has recently…

Quantum Physics · Physics 2023-04-04 Stephan De Bievre

Finding quantitative aspects of quantum phenomena which cannot be explained by any classical model has foundational importance for understanding the boundary between classical and quantum theory. It also has practical significance for…

Quantum Physics · Physics 2018-02-06 David Schmid , Robert W. Spekkens

The discovery of quantum key distribution by Bennett and Brassard (BB84) bases on the fundamental quantum feature: incompatibility of measurements of quantum non-commuting observables. In 1991 Ekert showed that cryptographic key can be…

We derive a family of inequalities involving different phase-space distributions of a quantum state which have to be fulfilled by any classical state. The violation of these inequalities is a clear signature of nonclassicality. Our approach…

Quantum Physics · Physics 2020-04-03 Martin Bohmann , Elizabeth Agudelo

We introduce an experimental test for ruling out classical explanations for the statistics obtained when measuring arbitrary observables at arbitrary times using individual detectors. This test requires some trust in the measurements,…

Quantum Physics · Physics 2019-03-27 Patrick P. Potts

The discovery of quantum key distribution by Bennett and Brassard (BB84) bases on the fundamental quantum feature: incompatibility of measurements of quantum non-commuting observables. In 1991 Ekert showed that cryptographic key can be…

We consider the probabilistic description of nonrelativistic, spinless one-particle classical mechanics, and immerse the particle in a deformed noncommutative phase space in which position coordinates do not commute among themselves and…

High Energy Physics - Theory · Physics 2010-10-27 B. Muthukumar

In 1926, Dirac stated that quantum mechanics can be obtained from classical theory through a change in the only rule. In his view, classical mechanics is formulated through commutative quantities (c-numbers) while quantum mechanics requires…

Quantum Physics · Physics 2012-11-20 Vladimir V. Kisil