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We formulate the accuracy of quantum measurement for a qubit system in terms of a 3 by 3 matrix. This matrix, which we refer to as the accuracy matrix, can be calculated from a positive operator-valued measure (POVM) corresponding to the…

Quantum Physics · Physics 2009-11-13 Takahiro Sagawa , Masahito Ueda

We present an iterative algorithm based on semidefinite programming (SDP) for computing the quantum smooth max-mutual information $I^\varepsilon_{\max}(\rho_{AB})$ of bipartite quantum states in any dimension. The algorithm is accurate if a…

Quantum Physics · Physics 2025-10-21 Christopher Popp , Tobias C. Sutter , Beatrix C. Hiesmayr

In quantum-state tomography on sources with quantum degrees of freedom of large Hilbert spaces, inference of quantum states of light for instance, a complete characterization of the quantum states for these sources is often not feasible…

Quantum Physics · Physics 2013-11-14 Yong Siah Teo , Jaroslav Rehacek , Zdenek Hradil

For finite-dimensional bipartite quantum systems, we find the exact size of the largest balls, in spectral $l_p$ norms for $1 \le p \le \infty$, of separable (unentangled) matrices around the identity matrix. This implies a simple and…

Quantum Physics · Physics 2009-11-07 Leonid Gurvits , Howard Barnum

The superposition of quantum states lies at the heart of physics and has been recently found to serve as a versatile resource for quantum information protocols, defining the notion of quantum coherence. In this contribution, we report on…

Quantum Physics · Physics 2019-10-16 Valeria Cimini , Ilaria Gianani , Marco Sbroscia , Jan Sperling , Marco Barbieri

Mutually unbiased bases determine an optimal set of measurements to extract complete information about the quantum state of a system. However, quite often a priori information about the state exist, making some of the measurement bases…

Quantum Physics · Physics 2015-06-12 A. B. Klimov , G. Bjork , L. L. Sanchez-Soto

The state that an observer attributes to a quantum system depends on the information available to that observer. If two or more observers have different information about a single system, they will in general assign different states. Is…

Quantum Physics · Physics 2007-05-23 Todd A. Brun

It is shown that generic N-party pure quantum states (with equidimensional subsystems) are uniquely determined by their reduced states of just over half the parties; in other words, all the information in almost all N-party pure states is…

Quantum Physics · Physics 2009-11-10 Nick S. Jones , Noah Linden

A definition of the nonadditive (nonextensive) conditional entropy indexed by q is presented. Based on the composition law in terms of it, the Shannon-Khinchin axioms are generalized and the uniqueness theorem is established for the Tsallis…

Quantum Physics · Physics 2007-05-23 Sumiyoshi Abe , A. K. Rajagopal

Identifying which correlations among distant observers are possible within our current description of Nature, based on quantum mechanics, is a fundamental problem in Physics. Recently, information concepts have been proposed as the key…

Quantum Physics · Physics 2012-01-16 Rodrigo Gallego , Lars Erik Würflinger , Antonio Acín , Miguel Navascués

Although quantum entanglement has already been verified experimentally and applied in quantum computing, quantum sensing and quantum networks, most of the existing measures cannot characterize the entanglement faithfully. In this work, by…

Quantum Physics · Physics 2023-01-10 Zhi-Xiang Jin , Shao-Ming Fei , Xianqing Li-Jost , Cong-Feng Qiao

Quantum mutual information (QMI) not only displays the mutual information in the system but also demonstrates some quantum correlation beyond entanglement. We explore here the two alternatives of multipartite quantum mutual information…

Quantum Physics · Physics 2023-09-01 Yu Guo , Lizhong Huang

We analyze the trade-off between the amounts of information obtainable on complementary properties of a qubit state by simultaneous measurements. We consider a "state discrimination" scenario wherein the same measurements are repeated, but…

Quantum Physics · Physics 2009-03-26 Noam Erez , Daniel Jacobs , Gershon Kurizki

We introduce a new kind of quantum measurement that is defined to be symmetric in the sense of uniform Fisher information across a set of parameters that injectively represent pure quantum states in the neighborhood of a fiducial pure…

Quantum Physics · Physics 2016-05-11 Nan Li , Christopher Ferrie , Jonathan A. Gross , Amir Kalev , Carlton M. Caves

Since masking of quantum information was introduced by Modi et al. in [PRL 120, 230501 (2018)], many discussions on this topic have been published. In this paper, we consider relationship between quantum multipartite maskers (QMMs) and…

Quantum Physics · Physics 2020-05-22 Huaixin Cao , Yuxing Du , Zhihua Guo , Kanyuan Han , Chuan Yan

We consider a quantum state shared between many distant locations, and define a quantum information processing primitive, state merging, that optimally merges the state into one location. As announced in [Horodecki, Oppenheim, Winter,…

Quantum Physics · Physics 2008-06-12 Michal Horodecki , Jonathan Oppenheim , Andreas Winter

Commutators are essential in quantum information theory, influencing quantum state symmetries and information storage robustness. This paper systematically investigates the characteristics of bipartite and multipartite quantum states…

Quantum Physics · Physics 2025-04-15 Shu Li , Jie Wang , Binfeng Wang , Lin Chen

We study the relation between the quantum conditional mutual information and the quantum $\alpha$-R\'enyi divergences. Considering the totally antisymmetric state we show that it is not possible to attain a proper generalization of the…

Quantum Physics · Physics 2015-06-23 Paul Erker

Suppose N parties describe the state of a quantum system by N possibly different density operators. These N state assignments represent the beliefs of the parties about the system. We examine conditions for determining whether the N state…

Quantum Physics · Physics 2009-11-07 Carlton M. Caves , Christopher A. Fuchs , Ruediger Schack

The entanglement quantification and classification of multipartite quantum states are two important research fields in quantum information. In this work, we study the entanglement of arbitrary-dimensional multipartite pure states by looking…

Quantum Physics · Physics 2013-06-18 Hui Li , Shuhao Wang , Jianlian Cui , Gui-Lu Long
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