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Interaction-free measurement and quantum interrogation schemes can help in the detection of particles without interacting with them in a classical sense. We present a density matrix study of a quantum interrogation system designed for…

Quantum Physics · Physics 2007-05-23 Juan Carlos Garcia-Escartin , Pedro Chamorro-Posada

Impressive progress has been made in the past decade in the study of technological applications of varied types of quantum systems. With industry giants like IBM laying down their roadmap for scalable quantum devices with more than…

Quantum Physics · Physics 2021-09-15 Rishabh Gupta , Sabre Kais , Raphael D. Levine

Bounds analogous to entropic uncertainty relations allow one to design practical tests to detect quantum entanglement by a collective measurement performed on several copies of the state analyzed. This approach, initially worked out for…

Quantum Physics · Physics 2013-01-04 Łukasz Rudnicki , Zbigniew Puchała , Paweł Horodecki , Karol Życzkowski

The problem of of how many entangled or, respectively, separable states there are in the set of all quantum states is investigated. We study to what extent the choice of a measure in the space of density matrices describing N--dimensional…

Quantum Physics · Physics 2009-10-31 Karol Zyczkowski

We present a kind of construction for a class of special matrices with at most two different eigenvalues, in terms of some interesting multiplicators which are very useful in calculating eigenvalue polynomials of these matrices. This class…

Quantum Physics · Physics 2009-11-10 Shao-Ming Fei , Xianqing Li-Jost

In quantum operations, probabilities characterise both the degree of the success of a state transformation and, as density operator eigenvalues, the degree of mixedness of the final state. We give a unified treatment of pure-to-pure state…

Quantum Physics · Physics 2009-11-07 Anthony Chefles

In this paper, we examine the state art of quantum computing and analyze its potential effects in scientific computing and cybersecurity. Additionally, a non-technical description of the mechanics of the listed form of computing is provided…

Popular Physics · Physics 2021-05-21 Giovanny Espitia

A survey of various concepts in quantum information is given, with a main emphasis on the distinguishability of quantum states and quantum correlations. Covered topics include generalized and least square measurements, state discrimination,…

Quantum Physics · Physics 2015-06-22 Dominique Spehner

In ordinary, non-relativistic, quantum physics, time enters only as a parameter and not as an observable: a state of a physical system is specified at a given time and then evolved according to the prescribed dynamics. While the state can,…

Quantum Physics · Physics 2013-02-13 Joseph Fitzsimons , Jonathan Jones , Vlatko Vedral

We discuss the concept of connection states (or connection matrices) that describe posterior ensembles, post-selected according to the outcomes of a quantum measurement. Connection matrices allow one to obtain results of any weak and some…

Quantum Physics · Physics 2013-08-02 Abraham G. Kofman , Sahin K. Ozdemir , Franco Nori

We present a method for quantum state tomography that enables the efficient estimation, with fixed precision, of any of the matrix elements of the density matrix of a state, provided that the states from the basis in which the matrix is…

Quantum Physics · Physics 2015-06-12 Ariel Bendersky , Juan Pablo Paz

Generalizing the notion of relative entropy, the difference between a priori and a posteriori relative entropy for quantum systems is drawn. The former, known as quantum relative entropy, is associated with quantum states recognition. The…

Quantum Physics · Physics 2007-05-23 Roman R. Zapatrin

When discriminating between two pure quantum states, there exists a quantitative tradeoff between the information retrieved by the measurement and the disturbance caused on the unknown state. We derive the optimal tradeoff and provide the…

Quantum Physics · Physics 2007-05-23 Francesco Buscemi , Massimiliano F. Sacchi

We consider a generalized model of repeated quantum interactions, where a system $\mathcal{H}$ is interacting in a random way with a sequence of independent quantum systems $\mathcal{K}_n, n \geq 1$. Two types of randomness are studied in…

Quantum Physics · Physics 2015-02-12 Ion Nechita , Clément Pellegrini

We study the relationship between the entanglement, mixedness and energy of two-qubit and two-mode Gaussian quantum states. We parametrize the set of allowed states of these two fundamentally different physical systems using measures of…

Quantum Physics · Physics 2009-11-13 Derek McHugh , Mario Ziman , Vladimir Buzek

In this article we study relationship between three measures of distinguishability of quantum states called as divergence, relative entropy and the substate property.

Quantum Physics · Physics 2007-05-23 Rahul Jain , Jaikumar Radhakrishnan , Pranab Sen

Sir Rudolph Peierls, in a reply to John Bell's last critique of the state of our understanding of quantum mechanics, maintained that it is easy to give an acceptable account of the physical significance of the quantum theory. The key is to…

Quantum Physics · Physics 2007-05-23 N. David Mermin

When it comes to discriminating between two quantum states, trace distance is one of the well-known metrics used in quantum computation and quantum information theory. While there are several quantum algorithms for calculating the trace…

Quantum Physics · Physics 2026-04-08 Sanchita Ghosh , Anumita Mukhopadhyay , Anindita Bera , Prasenjit Deb , Shibdas Roy

New algorithm for quantum state estimation based on the maximum likelihood estimation is proposed. Existing techniques for state reconstruction based on the inversion of measured data are shown to be overestimated since they do not…

Quantum Physics · Physics 2009-10-30 Zdenek Hradil

The relation between entanglement entropy and the computational difficulty of classically simulating Quantum Mechanics is briefly reviewed. Matrix product states are proven to provide an efficient representation of one-dimensional quantum…

Quantum Physics · Physics 2008-11-26 Jose I. Latorre