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I derive a tight bound between the quality of estimating the state of a single copy of a $d$-level system, and the degree the initial state has to be altered in course of this procedure. This result provides a complete analytical…

Quantum Physics · Physics 2009-11-06 Konrad Banaszek

Quantum measurements can be described by operators that assign conditional probabilities to different outcomes while also describing unavoidable physical changes to the system. Here, we point out that operators describing information gain…

Quantum Physics · Physics 2026-05-18 Hollis Williams , Holger F. Hofmann

In the general theory of quantum measurement, one associates a positive semidefinite operator on a $d$-dimensional Hilbert space to each of the $n$ possible outcomes of an arbitrary measurement. In the special case of a projective…

Quantum Physics · Physics 2021-11-23 Yizhou Liu , John B. DeBrota

In this paper we give a new way to quantify the folklore notion that quantum measurements bring a disturbance to the system being measured. We consider two observers who initially assign identical mixed-state density operators to a…

Quantum Physics · Physics 2009-11-06 Christopher A. Fuchs , Kurt Jacobs

We show that it is possible to control the trade-off between information gain and disturbance in generalized measurements of qudits by utilizing the programmable quantum processor. This universal quantum machine allows us to perform a…

Quantum Physics · Physics 2009-11-10 Marian Rosko , Vladimir Buzek , Paul Robert Chouha , Mark Hillery

A new measure of information in quantum mechanics is proposed which takes into account that for quantum systems the only feature known before an experiment is performed are the probabilities for various events to occur. The sum of the…

Quantum Physics · Physics 2009-11-06 Caslav Brukner , Anton Zeilinger

Any measurement is intended to provide information on a system, namely knowledge about its state. However, we learn from quantum theory that it is generally impossible to extract information without disturbing the state of the system or its…

Quantum Physics · Physics 2020-11-18 Giacomo Mauro D'Ariano , Paolo Perinotti , Alessandro Tosini

We report lowest-order series expansions for primary matrix functions of quantum states based on a perturbation theory for functions of linear operators. Our theory enables efficient computation of functions of perturbed quantum states that…

Quantum Physics · Physics 2023-03-24 Michael R Grace , Saikat Guha

In general, classical measurement statistics of a quantum measurement is disturbed by performing an additional incompatible quantum measurement beforehand. Using this observation, we introduce a state-independent definition of disturbance…

Quantum Physics · Physics 2016-05-04 S. S. Zhou , Shengjun Wu , H. F. Chau

We investigate the tradeoff between the quality of an approximate version of a given measurement and the disturbance it induces in the measured quantum system. We prove that if the target measurement is a non-degenerate von Neumann…

Quantum Physics · Physics 2019-01-23 Anna-Lena K. Hashagen , Michael M. Wolf

The notion of Shannon entropy is crucial for the theory of classical information. In quantum information theory, an analogous key role is played by the von Neumann entropy: quantum information processing is closely related to entropy…

Quantum Physics · Physics 2026-04-15 Arul Lakshminarayan , Karol Życzkowski

This document focuses on translating various information-theoretic measures of distinguishability for probability distributions into measures of distin- guishability for quantum states. These measures should have important appli- cations in…

Quantum Physics · Physics 2007-05-23 Christopher A. Fuchs

When the von Neumann entropy (VNE) of a system increases due to measurements, certain information is lost, some of which may be recoverable. We define information retrievability (IR) and information loss (IL) as functions of the density…

Quantum Physics · Physics 2025-03-27 Xing M. Wang

We present the amounts of information, fidelity, and reversibility obtained by arbitrary quantum measurements on completely unknown states. These quantities are expressed as functions of the singular values of a measurement operator…

Quantum Physics · Physics 2016-02-05 Hiroaki Terashima

The amount of extractable work from a physical system is fundamentally connected to the information available about its state, as illustrated by Maxwell's demon and the Gibbs paradox. In standard thermodynamic protocols involving…

Quantum Physics · Physics 2026-02-27 Tanmoy Biswas

The information provided by a classical measurement is unambiguously determined by the mutual information between the output results and the measured quantity. However, quantum mechanically there are at least two notions of information…

Quantum Physics · Physics 2007-05-23 Kurt Jacobs

Calculation of the quantum discord requires to find the minimum of the quantum conditional entropy $S(\rho^{AB}|\{\Pi^B_{k}\})$ over all measurements on the subsystem $B$. In this paper, we provide a simple relation for the conditional…

Here, we leverage recent advances in information theory to develop a novel method to characterise the dominant character of the high-order dependencies of quantum systems. To this end, we introduce the Q-information: an…

The traditional formalism of quantum measurement (hereafter ``TQM'') describes processes where some properties of quantum states are extracted and stored as classical information. While TQM is a natural and appropriate description of how…

Entanglement and coherence are two essential quantum resources for quantum information processing. A natural question arises of whether there are direct link between them. And by thinking about this question, we propose a new measure for…

Quantum Physics · Physics 2019-04-03 Xiao-Gang Fan , Wen-Yang Sun , Zhi-Yong Ding , Fei Ming , Huan Yang , Dong Wang , Liu Ye