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We study a generalization of the Wigner function to arbitrary tuples of hermitian operators. We show that for any collection of hermitian operators A1...An , and any quantum state there is a unique joint distribution on R^n, with the…

Quantum Physics · Physics 2020-07-09 René Schwonnek , Reinhard F. Werner

Just as a coherent state may be considered as a quantum point, its restriction to a factor space of the full Hilbert space can be interpreted as a quantum plane. The overlap of such a factor coherent state with a full pure state is akin to…

The negativity of the discrete Wigner functions (DWFs) is a measure of non-classicality and is often used to quantify the degree of quantum coherence in a system. The study of Wigner negativity and its evolution under different quantum…

Quantum Physics · Physics 2025-09-03 Jai Lalita , K. G. Paulson , Subhashish Banerjee

We present a technique to coarse-grain quantum states in a finite-dimensional Hilbert space. Our method is distinguished from other approaches by not relying on structures such as a preferred factorization of Hilbert space or a preferred…

Quantum Physics · Physics 2018-03-16 Ashmeet Singh , Sean M. Carroll

The integral of the Wigner function of a quantum mechanical system over a region or its boundary in the classical phase plane, is called a quasiprobability integral. Unlike a true probability integral, its value may lie outside the interval…

Quantum Physics · Physics 2009-11-10 A. J. Bracken , D. Ellinas , J. G. Wood

We show that partial transposition for pure and mixed two-particle states in a discrete $N$-dimensional Hilbert space is equivalent to a change in sign of a "momentum-like" variable of one of the particles in the Wigner function for the…

Quantum Physics · Physics 2017-05-29 Yehuda B. Band , Pier A. Mello

Binary quantum information can be fault tolerantly encoded in states defined in infinite dimensional Hilbert spaces. Such states define a computational basis, and permit a perfect equivalence between continuous and discrete universal…

Quantum Physics · Physics 2016-09-13 A. Ketterer , A. Keller , S. P. Walborn , T. Coudreau , P. Milman

In this project we examine several different quantum key distribution protocols which we divide into ones utilizing qubits whose Hilbert spaces are two dimensional and ones whose Hilbert space dimension is greater than two, these units of…

Quantum Physics · Physics 2024-02-05 Yuval Idan , Avihai Didi

Weyl's formulation of quantum mechanics opened the possibility of studying the dynamics of quantum systems both in infinite-dimensional and finite-dimensional systems. Based on Weyl's approach, generalized by Schwinger, a self-consistent…

Mathematical Physics · Physics 2015-06-05 Nicolae Cotfas , Daniela Dragoman

Wigner's quasi-probability distribution function in phase-space is a special (Weyl) representation of the density matrix. It has been useful in describing quantum transport in quantum optics; nuclear physics; decoherence (eg, quantum…

High Energy Physics - Theory · Physics 2008-11-26 Cosmas K Zachos

We have calculated the admittance of a two-dimensional quantum point contact (QPC) using a novel variant of the Wigner distribution function (WDF) formalism. In the semiclassical approximation, a Boltzman-like equation is derived for the…

Condensed Matter · Physics 2016-08-31 Igor E. Aronov , Gennady P. Berman , David K. Campbell , Sergey V. Dudiy

The possibility of constructing a complete, continuous Wigner function for any quantum system has been a subject of investigation for over 50 years. A key system that has served to illustrate the difficulties of this problem has been an…

Quantum Physics · Physics 2016-10-28 Todd Tilma , Mark J. Everitt , John H. Samson , William J. Munro , Kae Nemoto

In this work we have explored few tools in Quantum State Tomography for Continuous Variable Systems. The concept of quantum states in phase space representation is introduced in a simple manner by using a few statistical concepts. Unlike…

Quantum Physics · Physics 2019-12-12 Ludmila Botelho

We prove some abstract Wegner bounds for random self-adjoint operators. Applications include elementary proofs of Wegner estimates for discrete and continuous Anderson Hamiltonians with possibly sparse potentials, as well as Wegner bounds…

Mathematical Physics · Physics 2014-02-14 Mostafa Sabri

We show how sub-Planck phase-space structures in the Wigner function can be used to achieve Heisenberg-limited sensitivity in weak force measurements. Nonclassical states of harmonic oscillators, consisting of superpositions of coherent…

Quantum Physics · Physics 2009-11-11 F. Toscano , D. A. R. Dalvit , L. Davidovich , W. H. Zurek

We review the problem of state reconstruction in classical and in quantum physics, which is rarely considered at the textbook level. We review a method for retrieving a classical state in phase space, similar to that used in medical imaging…

Quantum Physics · Physics 2015-06-03 F. C. Khanna , P. A. Mello , M. Revzen

We study theoretically a double quantum dot hydrogen molecule in the GaAs conduction band as the basic elementary gate for a quantum computer with the electron spins in the dots serving as qubits. Such a two-dot system provides the…

Quantum Physics · Physics 2009-10-31 Xuedong Hu , S. Das Sarma

This paper presents a general coding method where data in a Hilbert space are represented by finite dimensional coding vectors. The method is based on empirical risk minimization within a certain class of linear operators, which map the set…

Machine Learning · Statistics 2011-09-05 Andreas Maurer Massimiliano Pontil

Discriminating between quantum computing architectures that can provide quantum advantage from those that cannot is of crucial importance. From the fundamental point of view, establishing such a boundary is akin to pinpointing the resources…

Quantum Physics · Physics 2021-03-23 Laura García-Álvarez , Cameron Calcluth , Alessandro Ferraro , Giulia Ferrini

We show how discrete squeezed states in an $N^{2}$-dimensional phase space can be properly constructed out of the finite-dimensional context. Such discrete extensions are then applied to the framework of quantum tomography and quantum…

Quantum Physics · Physics 2011-11-09 Marcelo A. Marchiolli , Maurizio Ruzzi , Diogenes Galetti