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Quantum state exclusion is the task of determining which states from a given set a system was not prepared in. We provide a complete solution to optimal quantum state exclusion for arbitrary sets of pure states generated by finite groups,…

Quantum Physics · Physics 2026-01-21 Arnau Diebra , Santiago Llorens , Emili Bagan , Gael Sentís , Ramon Muñoz-Tapia

We discuss the disturbance by measurements which unambiguously discriminate between given candidate states. We prove that such an optimal measurement necessarily changes distinguishable states indistinguishable when the inconclusive outcome…

Quantum Physics · Physics 2018-03-14 Ryuitiro Kawakubo , Tatsuhiko Koike

Quantum state discrimination is a fundamental information processing task that serves as a building block for numerous applications and provides implications at the foundational level. In this work, we consider minimum error discrimination…

Quantum Physics · Physics 2026-04-30 Tim Achenbach , Leevi Leppäjärvi , Hanwool Lee , Teiko Heinosaari

The discrimination of two nonorthogonal states is a fundamental element for secure and efficient communication. Quantum measurements of nonorthogonal coherent states can enhance information transfer beyond the limits of conventional…

Quantum Physics · Physics 2018-07-16 M. T. DiMario , F. E. Becerra

The uncertainty principle may be considered as giving rise to the notion of incompatibility of observables. A pack of quantum measurements that cannot be measured simultaneously is said to form a set of incompatible measurements. Every set…

Quantum Physics · Physics 2024-01-19 Kornikar Sen , Saronath Halder , Ujjwal Sen

We provide a solution of finding optimal measurement strategy for distinguishing between symmetric mixed quantum states. It is assumed that the matrix elements of at least one of the symmetric quantum states are all real and nonnegative in…

Quantum Physics · Physics 2009-11-10 Chih-Lung Chou , Li-Yi Hsu

Unambiguously distinguishing between nonorthogonal but linearly independent quantum states is a challenging problem in quantum information processing. In this work, an exact analytic solution to an optimum measurement problem involving an…

Quantum Physics · Physics 2009-11-13 M. A. Jafarizadeh , M. Rezaei , N. Karimi , A. R. Amiri

In this paper, we shall show that the question of quanum state unambiguous discrimination can be solved by reducing it to the known problem of quantum states filtering.

Quantum Physics · Physics 2015-09-01 Xiaohua Wu , Yu Shaolan , Zhou Tao

A quantum analog of the fundamental classical NOT gate is a quantum gate that would transform any input qubit state onto an orthogonal state. Intriguingly, this universal NOT gate is forbidden by the laws of quantum physics. This striking…

Quantum Physics · Physics 2015-06-19 M. Jezek , M. Micuda , I. Straka , M. Mikova , M. Dusek , J. Fiurasek

We consider one copy of a quantum system prepared with equal prior probability in one of two non-orthogonal entangled states of multipartite distributed among separated parties. We demonstrate that these two states can be optimally…

Quantum Physics · Physics 2013-05-29 Yi-Xin Chen , Dong Yang

Sequential methods for quantum hypothesis testing offer significant advantages over fixed-length approaches, which rely on a predefined number of state copies. Despite their potential, these methods remain underexplored for unambiguous…

Quantum Physics · Physics 2025-11-26 Jordi Pérez-Guijarro , Alba Pagès-Zamora , Javier R. Fonollosa

The quantum formalism permits one to discriminate sometimes between any set of linearly-independent pure states with certainty. We obtain the maximum probability with which a set of equally-likely, symmetric, linearly-independent states can…

Quantum Physics · Physics 2009-10-31 Anthony Chefles , Stephen M. Barnett

We propose and experimentally demonstrate non-destructive and noiseless removal (filtering) of vacuum states from an arbitrary set of coherent states of continuous variable systems. Errors i.e. vacuum states in the quantum information are…

Quantum Physics · Physics 2009-11-13 C. Wittmann , D. Elser , U. L. Andersen , R. Filip , P. Marek , G. Leuchs

It is shown that different distinguishability measures impose different orderings on ensembles of $N$ pure quantum states. This is demonstrated using ensembles of equally-probable, linearly independent, symmetrical pure states, with the…

Quantum Physics · Physics 2009-11-07 Anthony Chefles

We study the measurement for the unambiguous discrimination of two mixed quantum states that are described by density operators $\rho_1$ and $\rho_2$ of rank d, the supports of which jointly span a 2d-dimensional Hilbert space. Based on two…

Quantum Physics · Physics 2009-11-13 Ulrike Herzog

We consider the problem of designing an optimal quantum detector to minimize the probability of a detection error when distinguishing between a collection of quantum states, represented by a set of density operators. We show that the design…

Quantum Physics · Physics 2016-11-18 Yonina C. Eldar , Alexandre Megretski , George C. Verghese

We investigate how to determine whether the states of a set of quantum systems are identical or not. This paper treats both error-free comparison, and comparison where errors in the result are allowed. Error-free comparison means that we…

Quantum Physics · Physics 2015-06-26 Igor Jex , Erika Andersson , Anthony Chefles

We investigate the ability of a quantum measurement device to discriminate two states or, generically, two hypothesis. In full generality, the measurement can be performed a number $n$ of times, and arbitrary pre-processing of the states…

Quantum Physics · Physics 2017-04-26 Christoph Hirche , Masahito Hayashi , Emilio Bagan , John Calsamiglia

The problem of optimally discriminating between two completely unknown qubit states is generalized by allowing an error margin. It is visualized as a device---the programmable discriminator---with one data and two program ports, each fed…

Quantum Physics · Physics 2013-11-11 G. Sentís , E. Bagan , J. Calsamiglia , R. Muñoz-Tapia

A measurement strategy is developed for a new kind of hypothesis testing. It assigns, with minimum probability of error, the state of a quantum system to one or the other of two complementary subsets of a set of N given non-orthogonal…

Quantum Physics · Physics 2009-11-07 Ulrike Herzog , Janos A. Bergou