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The characterization of quantum features in large Hilbert spaces is a crucial requirement for testing quantum protocols. In the continuous variables encoding, quantum homodyne tomography requires an amount of measurements that increases…

Quantum Physics · Physics 2020-10-29 Valeria Cimini , Marco Barbieri , Nicolas Treps , Mattia Walschaers , Valentina Parigi

Quantum states can in a sense be thought of as generalizations of classical probability distributions, but are more powerful than probability distributions when used for computation or communication. Quantum speedup therefore requires some…

Quantum Physics · Physics 2014-08-04 Dan Stahlke

In this study, we introduce the concept of Classicality and derive Wigner inequalities that depend on two instants, with a potential extension to three instants. We explore the experimental feasibility of testing the violations of these…

Quantum Physics · Physics 2025-07-22 Efimova Anna , Nikitin Nikolay

The formalism of classical and quantum mechanics on phase space leads to symplectic and Heisenberg group representations, respectively. The Wigner functions give a representation of the quantum system using classical variables. The…

Quantum Physics · Physics 2007-05-23 Ajay Patwardhan

We show, under natural assumptions for qubit systems, that measurement-based quantum computations (MBQCs) which compute a non-linear Boolean function with high probability are contextual. The class of contextual MBQCs includes an example…

Quantum Physics · Physics 2013-08-28 Robert Raussendorf

Quantum inequalities are bounds on negative time-averages of the energy density of a quantum field. They can be used to rule out exotic spacetimes in general relativity. We study quantum inequalities for a scalar field with a background…

General Relativity and Quantum Cosmology · Physics 2014-07-16 Eleni-Alexandra Kontou , Ken D. Olum

In [Phys. Rev. A 70, 062101 (2004)] Gibbons et al. defined a class of discrete Wigner functions W to represent quantum states in a finite Hilbert space dimension d. I characterize a set C_d of states having non-negative W simultaneously in…

Quantum Physics · Physics 2007-05-23 Ernesto F. Galvao

The output randomness from a random number generator can be certified by observing the violation of quantum contextuality inequalities based on the Kochen-Specker theorem. Contextuality can be tested in a single quantum system, which…

Quantum Physics · Physics 2020-04-08 Mark Um , Qi Zhao , Junhua Zhang , Pengfei Wang , Ye Wang , Mu Qiao , Hongyi Zhou , Xiongfeng Ma , Kihwan Kim

Time series prediction is essential for human activities in diverse areas. A common approach to this task is to harness Recurrent Neural Networks (RNNs). However, while their predictions are quite accurate, their learning process is complex…

Quantum Physics · Physics 2025-05-30 Michał Siemaszko , Adam Buraczewski , Bertrand Le Saux , Magdalena Stobińska

Phase-space features of the Wigner flow are examined so to provide a set of continuity equations that describe the flux of quantum information in the phase-space. The reported results suggest that the non-classicality profile of anharmonic…

Quantum Physics · Physics 2019-09-24 Alex E. Bernardini , Orfeu Bertolami

In quantum mechanics, not everything that can be observed can be observed simultaneously. Observational data exhibits \emph{contextuality} -- a generalisation of nonlocality -- if the result of an observation is necessarily dependent on…

Quantum Physics · Physics 2026-03-13 Ask Ellingsen

Cabello-Severini-Winter and Abramsky-Hardy (building on the framework of Abramsky-Brandenburger) both provide classes of Bell and contextuality inequalities for very general experimental scenarios using vastly different mathematical…

Quantum Physics · Physics 2017-03-29 Nadish de Silva

There are two different and logically independent concepts of noncontextuality in quantum mechanics. First, an ontological (hidden variable) model for quantum mechanics is called noncontextual if every ontic (hidden) state determines the…

Quantum Physics · Physics 2022-03-03 Gábor Hofer-Szabó

This paper establishes a direct, robust and intimate connection between (i) non classicality tests for various quantum features, e.g., non-Boolean logic, quantum coherence, nonlocality, quantum entanglement, quantum discord; (ii) negative…

Quantum Physics · Physics 2021-10-26 Sooryansh Asthana , V. Ravishankar

Randomness is both a useful way to model natural systems and a useful tool for engineered systems, e.g. in computation, communication and control. Fully random transformations require exponential time for either classical or quantum…

Quantum Physics · Physics 2016-05-04 Fernando G. S. L. Brandao , Aram W. Harrow , Michal Horodecki

Quantum algorithms can deliver asymptotic speedups over their classical counterparts. However, there are few cases where a substantial quantum speedup has been worked out in detail for reasonably-sized problems, when compared with the best…

Quantum Physics · Physics 2019-07-24 Earl Campbell , Ankur Khurana , Ashley Montanaro

This work focuses on quantum reservoir computing and, in particular, on quantum Wiener architectures (qWiener), consisting of quantum linear dynamic networks with weak continuous measurements and classical nonlinear static readouts. We…

Quantum Physics · Physics 2026-01-09 Alessio Benavoli , Felix Binder

Driven by potential exponential speedups in business, security, and scientific scenarios, interest in quantum computing is surging. This interest feeds the development of quantum computing hardware, but several challenges arise in…

Quantum Physics · Physics 2024-09-11 Junghoon Chae , Chad A. Steed , Travis S. Humble

In a noncontextual hidden variable model of quantum theory, hidden variables determine the outcomes of every measurement in a manner that is independent of how the measurement is implemented. Using a generalization of this notion to…

Quantum Physics · Physics 2009-01-09 Robert W. Spekkens , D. H. Buzacott , A. J. Keehn , Ben Toner , G. J. Pryde

We reveal that the entropic uncertainty relation with a quantum memory is able to intrinsically connect local generic contextuality addressed in the pioneering work by Spekkens and nonlocal quantum resources such as entanglement and Bell…

Quantum Physics · Physics 2026-05-01 Wei Li , Min-Xuan Zhou , Yun-Hao Shi , Z. D. Wang , Heng Fan , Yan-Kui Bai
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