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Landauer's principle introduces a symmetry between computational and physical processes: erasure of information, a logically irreversible operation, must be underlain by an irreversible transformation dissipating energy. Monitoring micro-…

The nonadditivity of channel capacity is a defining feature that distinguishes quantum communication from classical communication. In the quantum realm, the channel capacity is determined by coherent information, which is defined through…

Quantum Physics · Physics 2026-05-19 Yu Guo , Bo-Xuan Wang , Xiao-Min Hu , Yun-Feng Huang , Chuan-Feng Li , Guang-Can Guo , Bi-Heng Liu

It is well known that the quantum mutual information and its conditional version do not increase under local channels. I this paper we show that the recently established lower semicontinuity of the quantum conditional mutual information…

Quantum Physics · Physics 2021-09-28 M. E. Shirokov

We study in detail a very natural metric for quantum states. This new proposal has two basic ingredients: entropy and purification. The metric for two mixed states is defined as the square root of the entropy of the average of…

Quantum Physics · Physics 2011-12-23 P. W. Lamberti , M. Portesi , J. Sparacino

The detection and quantification of non-Markovianity, a.k.a. memory, in quantum systems is a central problem in the theory of open quantum systems. There memory is as a result of the interaction between the system and its environment.…

Quantum Physics · Physics 2025-12-17 Jorge Tabanera-Bravo , Aljaž Godec

One of the defining traits of quantum mechanics is the uncertainty principle which was originally expressed in terms of the standard deviation of two observables. Alternatively, it can be formulated using entropic measures, and can also be…

Quantum Physics · Physics 2015-09-30 Göktuğ Karpat , Jyrki Piilo , Sabrina Maniscalco

Relevance of key quantum information measures for analysis of quantum systems is discussed. It is argued that possible ways of measuring quantum information are based on compatibility/incompatibility of the quantum states of a quantum…

Quantum Physics · Physics 2015-06-26 B. A. Grishanin , V. N. Zadkov

Information must take up space, must weigh, and its flux must be limited. Quantum limits on communication and information storage leading to these conclusions are here described. Quantum channel capacity theory is reviewed for both steady…

Quantum Physics · Physics 2015-06-26 Jacob D. Bekenstein , Marcelo Schiffer

In recent years, several measures have been proposed for characterizing the coherence of a given quantum state. We derive several results that illuminate how these measures behave when restricted to pure states. Notably, we present an…

Quantum Physics · Physics 2016-10-26 Jianxin Chen , Shane Grogan , Nathaniel Johnston , Chi-Kwong Li , Sarah Plosker

We derive explicit bounds for the average entropy characterizing measurements of a pure quantum state of size $N$ in $L$ orthogonal bases. Lower bounds lead to novel entropic uncertainty relations, while upper bounds allow us to formulate…

Entropy is a fundamental concept in quantum information theory that allows to quantify entanglement and investigate its properties, for example its monogamy over multipartite systems. Here, we derive variational formulas for relative…

Quantum Physics · Physics 2024-05-21 Mario Berta , Marco Tomamichel

In [Berta 2014 Entanglement], uncertainty relations in the presence of quantum memory was formulated for mutually unbiased bases using conditional collision entropy. In this paper, we generalize their results to the mutually unbiased…

Quantum Physics · Physics 2018-10-03 Kun Wang , Nan Wu , Fangmin Song

Measurement outcomes of a quantum state can be genuinely random (unpredictable) according to the basic laws of quantum mechanics. The Heisenberg-Robertson uncertainty relation puts constrains on the accuracy of two noncommuting observables.…

Quantum Physics · Physics 2017-09-13 Xiao Yuan , Ge Bai , Tianyi Peng , Xiongfeng Ma

In this work, we use the theory of quantum states over time to define an entropy $S(\rho,\mathcal{E})$ associated with quantum processes $(\rho,\mathcal{E})$, where $\rho$ is a state and $\mathcal{E}$ is a quantum channel responsible for…

Quantum Physics · Physics 2023-07-24 James Fullwood , Arthur J. Parzygnat

Quantum metrology based on quantum entanglement and quantum coherence improves the accuracy of measurement. In this paper, we briefly review the schemes of quantum metrology in various complex systems, including non-Markovian noise,…

Quantum Physics · Physics 2024-01-18 Qing Ai , Yang-Yang Wang , Jing Qiu

The study of mutual entropy (information) and capacity in classica l system was extensively done after Shannon by several authors like Kolmogor ov and Gelfand. In quantum systems, there have been several definitions of t he mutual entropy…

Quantum Physics · Physics 2007-05-23 Masanori Ohya

The non-classical nature of quantum states, often illustrated using entanglement measures or quantum discord, constitutes a resource for quantum information protocols. However, the non-classicality of a quantum system cannot be encapsulated…

Quantum Physics · Physics 2016-02-18 Carole Addis , Teiko Heinosaari , Jukka Kiukas , Elsi-Mari Laine , Sabrina Maniscalco

Subentropy is an entropy-like quantity that arises in quantum information theory; for example, it provides a tight lower bound on the accessible information for pure state ensembles, dual to the von Neumann entropy upper bound in Holevo's…

Quantum Physics · Physics 2015-12-31 Nilanjana Datta , Tony Dorlas , Richard Jozsa , Fabio Benatti

Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we first give an uncertainty-like expression relating the coherence and the entropy of quantum system. This…

Quantum Physics · Physics 2015-07-15 Zhengjun Xi , Yongming Li , Heng Fan

We analyze general enough models of repeated indirect measurements in which a quantum system interacts repeatedly with randomly chosen probes on which Von Neumann direct measurements are performed. We prove, under suitable hypotheses, that…

Mathematical Physics · Physics 2015-06-05 Michel Bauer , Tristan Benoist , Denis Bernard