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Quantum entropy inequalities are studied. Some quantum entropy inequalities are obtained by several methods. For entanglement breaking channel, we show that the entanglement-assisted classical capacity is upper bounded by $\log d$. A…

Quantum Physics · Physics 2009-11-07 Heng Fan

Quantum physics, despite its observables being intrinsically of a probabilistic nature, does not have a quantum entropy assigned to them. We propose a quantum entropy that quantify the randomness of a pure quantum state via a conjugate pair…

Quantum Physics · Physics 2022-10-05 Davi Geiger , Zvi M. Kedem

We establish new integral inequalities for the numerical radius and the operator norm of bounded linear operators on Hilbert spaces. Our results refine classical triangle-type and operator matrix inequalities by incorporating convex…

Functional Analysis · Mathematics 2026-02-17 Shiva Sheybani , Hamid Reza Moradi , Mohammad Sababheh

We derive new characterisations of the matrix $\mathrm{\Phi}$-entropy functionals introduced in [Electron.~J.~Probab., 19(20): 1--30, 2014]. Notably, all known equivalent characterisations of the classical $\Phi$-entropies have their matrix…

Mathematical Physics · Physics 2016-08-25 Hao-Chung Cheng , Min-Hsiu Hsieh

We describe an interpretation of quantum mechanics based on reduced density matrices of sub-systems from which the standard Copenhagen interpretation emerges as an effective description for macro-systems. The interpretation is a modal one,…

Quantum Physics · Physics 2013-12-18 Timothy J. Hollowood

Relativistic effects affect nearly all notions of quantum information theory. The vacuum behaves as a noisy channel, even if the detectors are perfect. The standard definition of a reduced density matrix fails for photon polarization…

Quantum Physics · Physics 2007-05-23 Asher Peres , Daniel R. Terno

After an elementary derivation of Bell's inequality, several forms of expectation functions for two-valued observables are discussed. Special emphasis is given to hypothetical stronger-than quantum expectation functions which give rise to a…

Quantum Physics · Physics 2016-09-08 Kurt Krenn , Karl Svozil

The joint convexity of the map $(X,A) \mapsto X^* A^{-1} X$, an integral representation of operator convex functions, and an observation of Ando are used to obtain a simple proof of both the joint convexity of relative entropy and a trace…

Quantum Physics · Physics 2022-09-07 Mary Beth Ruskai

In this work the Quantum and Statistical Mechanics of the Early Universe, i.e. at Planck scale, is considered as a deformation of the well-known theories. In so doing the primary object under deformation in both cases is the density matrix.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. E. Shalyt-Margolin

We show that Frenkel's integral representation of the quantum relative entropy provides a natural framework to derive continuity bounds for quantum information measures. Our main general result is a dimension-independent semi-continuity…

Quantum Physics · Physics 2025-03-04 Mario Berta , Ludovico Lami , Marco Tomamichel

The novel concept of quantum logical entropy is presented and analyzed. We prove several basic properties of this entropy with regard to density matrices. We hereby motivate a different approach for the assignment of quantum entropy to…

Quantum Physics · Physics 2017-11-27 Boaz Tamir , Eliahu Cohen

We introduce a new interpretation of quantum mechanics by examining the Einstein, Podolsky and Rosen's (EPR) paradox and Bell's inequality experiments under the assumption that the vacuum has an inhomogeneous texture for energy levels below…

Quantum Physics · Physics 2020-02-21 Yoko Suzuki , Kevin M Mertes

Errors in Eberly's derivation of several Bell inequalities are pointed out: (1) it is based on an equation that is incorrect; (2) it uses neither two-particle states nor locality to derive Bell's inequalities and; (3) it does not use…

Quantum Physics · Physics 2009-02-11 Luiz Carlos Ryff

This paper represents an extended version of an earlier note [10]. The concept of weighted entropy takes into account values of different outcomes, i.e., makes entropy context-dependent, through the weight function. We analyse analogs of…

Probability · Mathematics 2017-10-31 Mark Kelbert , Izabella Stuhl , Yuri Suhov

We show that the "practical" Bell inequalities, which use intensities as the observed variables, commonly used in quantum optics and widely accepted in the community, suffer from an inherent loophole, which severely limits the range of…

Quantum Physics · Physics 2016-10-07 Marek Zukowski , Marcin Wiesniak , Wieslaw Laskowski

We review the fundamental properties of the quantum relative entropy for finite-dimensional Hilbert spaces. In particular, we focus on several inequalities that are related to the second law of thermodynamics, where the positivity and the…

Statistical Mechanics · Physics 2023-04-18 Takahiro Sagawa

The density matrix is a positive semidefinite operator of trace 1 characterizing the state of a quantum system. We consider the inverse problem to reconstruct such density matrices from indirect measurements, also known as quantum state…

Numerical Analysis · Mathematics 2026-03-06 Florian Oberender , Thorsten Hohage

A new notion of partition-determined functions is introduced, and several basic inequalities are developed for the entropy of such functions of independent random variables, as well as for cardinalities of compound sets obtained using these…

Information Theory · Computer Science 2012-06-05 Mokshay Madiman , Adam Marcus , Prasad Tetali

Upper and lower bounds are obtained for the joint entropy of a collection of random variables in terms of an arbitrary collection of subset joint entropies. These inequalities generalize Shannon's chain rule for entropy as well as…

Information Theory · Computer Science 2024-05-07 Mokshay Madiman , Prasad Tetali

In this article, we prove that convex functions and log-convex functions obey certain general refinements that lead to several refinements and reverses of well known inequalities for matrices, including Young's inequality, Heinz inequality,…

Functional Analysis · Mathematics 2016-06-28 Mohammad Sababheh