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The persistence of sub-Planck structure in phase space with loss of coherence is demonstrated in a mixed state, which comprises two terms in the density matrix. Its utility in carrying out Heisenberg-limited measurement and quantum…

Quantum Physics · Physics 2018-06-05 Asmita Kumari , A. K. Pan , P. K. Panigrahi

A fundamental property of compact groups and compact quantum groups is the existence and uniqueness of a left and right invariant probability -- the Haar measure. This is a natural playground for classical and quantum probability, provided…

Operator Algebras · Mathematics 2024-05-10 Benoit Collins

We build a general quantum state tomography framework that makes use of machine learning techniques to reconstruct quantum states from a given set of coincidence measurements. For a wide range of pure and mixed input states we demonstrate…

Quantum Physics · Physics 2020-06-09 Sanjaya Lohani , Brian T. Kirby , Michael Brodsky , Onur Danaci , Ryan T. Glasser

The relations between quantum coherence and quantum interference are discussed. A general method for generation of quantum coherence through interference-induced state selection is introduced and then applied to `simple' atomic systems…

Quantum Physics · Physics 2007-05-23 Jean Claude Garreau

Anticoherent spin states have isotropic low-order spin moments and are relevant to direction-independent metrology and quantum reference-frame alignment. In contrast to pure states, for mixed states such isotropy may originate either from…

Quantum Physics · Physics 2026-05-29 Jérôme Denis , Tara Lacaille , John Martin , Eduardo Serrano-Ensástiga

Quantifying entanglement is a work in progress which is important for the active field of quantum information and computation. A measure of bipartite pure state entanglement is proposed here, named entanglement coherence, which is…

Quantum Physics · Physics 2022-02-15 Neha Pathania , Tabish Qureshi

A unified conceptual foundation of classical and quantum physics is given, free of undefined terms. Ensembles are defined by extending the `probability via expectation' approach of Whittle to noncommuting quantities. This approach carries…

Quantum Physics · Physics 2007-05-23 Arnold Neumaier

Consider a mixed quantum mechanical state, describing a statistical ensemble in terms of an arbitrary density operator $\rho$ of low purity, $\tr\rho^2\ll 1$, and yielding the ensemble averaged expectation value $\tr(\rho A)$ for any…

Statistical Mechanics · Physics 2009-11-13 Peter Reimann

We analyze mean fidelity between random density matrices of size N, generated with respect to various probability measures in the space of mixed quantum states: Hilbert-Schmidt measure, Bures (statistical) measure, the measures induced by…

Quantum Physics · Physics 2009-11-10 Karol Zyczkowski , Hans-Jurgen Sommers

We study a coarse-graining map arising from incomplete and imperfect addressing of particles in a multipartite quantum system. In its simplest form, corresponding to a two-qubit state, the resulting channel produces a convex mixture of the…

Quantum Physics · Physics 2026-04-30 K. Uriostegui , C. Pineda , C. Chryssomalakos , V. Rascón Barajas , I. Vázquez Mota

Quantum coherence, which quantifies the superposition properties of a quantum state, plays an indispensable role in quantum resource theory. A recent theoretical work [Phys. Rev. Lett. \textbf{116}, 070402 (2016)] studied the manipulation…

Quantum Physics · Physics 2017-10-02 Kang-Da Wu , Zhibo Hou , Han-Sen Zhong , Yuan Yuan , Guo-Yong Xiang , Chuan-Feng Li , Guang-Can Guo

Entanglement plays an important role in quantum communication, algorithms, and error correction. Schmidt coefficients are correlated to the eigenvalues of the reduced density matrix. These eigenvalues are used in Von Neumann entropy to…

Quantum Physics · Physics 2014-09-25 Anmer Daskin , Ananth Grama , Sabre Kais

We analytically calculate the average value of i-th largest Schmidt coefficient for random pure quantum states. Schmidt coefficients, i.e., eigenvalues of the reduced density matrix, are expressed in the limit of large Hilbert space size…

Quantum Physics · Physics 2007-05-23 Marko Znidaric

The statistical behaviour of the smallest eigenvalue has important implications for systems which can be modeled using a Wishart-Laguerre ensemble, the regular one or the fixed trace one. For example, the density of the smallest eigenvalue…

Mathematical Physics · Physics 2017-08-01 Santosh Kumar , Bharath Sambasivam , Shashank Anand

Entangled multipartite states are resources for universal quantum computation, but they can also give rise to ensembles of unitary transformations, a topic usually studied in the context of random quantum circuits. Using several graph state…

Quantum Physics · Physics 2016-05-25 Peter S. Turner , Damian Markham

So-called average subsystem entropies are defined by first taking partial traces over some pure state to define density matrices, then calculating the subsystem entropies, and finally averaging over the pure states to define the average…

Quantum Physics · Physics 2017-11-02 Ana Alonso-Serrano , Matt Visser

The quantum anomaly of a global symmetry is known to strongly constrain the allowed low-energy physics in a clean and isolated quantum system. However, the effect of quantum anomalies in disordered systems is much less understood,…

Strongly Correlated Electrons · Physics 2025-03-12 Yichen Xu , Chao-Ming Jian

Given a preferred orthonormal basis $B$ in the Hilbert space of a quantum system we define a measure of the coherence generating power of a unitary operation with respect to $B$. This measure is the average coherence generated by the…

Quantum Physics · Physics 2017-05-10 Paolo Zanardi , Georgios Styliaris , Lorenzo Campos Venuti

The resource theory of coherence studies the operational value of superpositions in quantum technologies. A key question in this theory concerns the efficiency of manipulation and interconversion of this resource. Here we solve this…

Quantum Physics · Physics 2019-03-13 Thomas Theurer , Alexander Streltsov , Martin B. Plenio

Quantifying coherence and entanglement is extremely important in quantum information processing. Here, we present numerical and analytical results for the geometric measure of coherence, and also present numerical results for the geometric…

Quantum Physics · Physics 2020-08-27 Zhou Zhang , Yue Dai , Yuli Dong , Chengjie Zhang
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