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We consider the problem of determining the mixed quantum state of a large but finite number of identically prepared quantum systems from data obtained in a sequence of ideal (von Neumann) measurements, each performed on an individual copy…

Quantum Physics · Physics 2009-11-10 Franz Embacher , Heide Narnhofer

Quantum hypothesis testing is an important tool for quantum information processing. Two main strategies have been widely adopted: in a minimum error discrimination strategy, the average error probability is minimized; while in an…

Quantum Physics · Physics 2020-11-25 Quntao Zhuang

We put the pure-state decomposition mathematical property of a mixed state to a physical test. We begin by characterizing all the possible decompositions of a rank-two mixed state by means of the complex overlap between two involved states.…

Quantum Physics · Physics 2015-05-20 Luis Roa , Alejandra Maldonad-Trapp , Marcelo Alid

We derive a general lower bound on the minimum-error probability for {\it ambiguous discrimination} between arbitrary $m$ mixed quantum states with given prior probabilities. When $m=2$, this bound is precisely the well-known Helstrom…

Quantum Physics · Physics 2009-11-13 Daowen Qiu

In the task of discriminating between nonorthogonal quantum states from multiple copies, the key parameters are the error probability and the resources (number of copies) used. Previous studies have considered the task of minimizing the…

We study discrimination of m quantum measurements in the scenario when the unknown measurement with n outcomes can be used only once. We show that ancilla-assisted discrimination procedures provide a nontrivial advantage over simple…

Quantum Physics · Physics 2014-12-01 Michal Sedlak , Mario Ziman

This work investigates which sets of quantum states give rise to the highest achievable success probability in minimum-error state discrimination if multiple copies of the unknown state are given. Specifically, we consider uniformly…

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

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

We consider a fixed quantum measurement performed over $n$ identical copies of quantum states. Using a rigorous notion of distinguishability We consider a fixed quantum measurement performed over $n$ identical copies of quantum states.…

Quantum Physics · Physics 2007-05-23 Lev B. Levitin , Tommaso Toffoli , Zac D. Walton

In this paper, we introduce a mixed form of ambiguous and unambiguous quantum state discriminations, and show that the mixed form has higher success probability than the unambiguous quantum state discriminations.

Quantum Physics · Physics 2015-12-08 Sunho Kim , Junde Wu , Minhyung Cho

A set of quantum states can be unambiguously discriminated if and only if they are linearly independent. However, for a linearly dependent set, if C copies of the state are available, then the resulting C particle states may form a linearly…

Quantum Physics · Physics 2009-11-07 Anthony Chefles

We show how to optimally discriminate between K distinct quantum states, of which N copies are available, using one-at-a-time interactions with each of the N copies. While this task (famously) requires joint measurements on all N copies, we…

Quantum Physics · Physics 2012-02-01 Robin Blume-Kohout , Sarah Croke , Michael Zwolak

The optimal discrimination of non-orthogonal quantum states with minimum error probability is a fundamental task in quantum measurement theory as well as an important primitive in optical communication. In this work, we propose and…

Quantum Physics · Physics 2009-11-13 C. Wittmann , M. Takeoka , K. N. Cassemiro , M. Sasaki , G. Leuchs , U. L. Andersen

We introduce a measure of the compatibility between quantum states--the likelihood that two density matrices describe the same object. Our measure is motivated by two elementary requirements, which lead to a natural definition. We list some…

Quantum Physics · Physics 2009-11-07 David Poulin , Robin Blume-Kohout

Discrete structures in Hilbert space play a crucial role in finding optimal schemes for quantum measurements. We solve the problem whether a complete set of five iso-entangled mutually unbiased bases exists in dimension four, providing an…

Quantum Physics · Physics 2020-03-10 Jakub Czartowski , Dardo Goyeneche , Markus Grassl , Karol Życzkowski

We consider unambiguous discrimination of two separable bipartite states, one being pure and the other being a rank-2 mixed state. There is a gap between the optimal success probability under global measurements and the one achieved by…

Quantum Physics · Physics 2007-09-21 Masato Koashi , Fumitaka Takenaga , Takashi Yamamoto , Nobuyuki Imoto

We consider an unambiguous identification of an unknown coherent state with one of two unknown coherent reference states. Specifically, we consider two modes of an electromagnetic field prepared in unknown coherent states alpha_1 and…

Quantum Physics · Physics 2008-12-11 Michal Sedlak , Mario Ziman , Ondrej Pribyla , Vladimir Buzek , Mark Hillery

We consider the discrimination of two-party quantum states and provide a quantum data-hiding scheme using two-qubit separable states. We first provide a bound on the optimal local discrimination of two-party quantum states, and establish a…

Quantum Physics · Physics 2025-12-18 Donghoon Ha , Jeong San Kim

The task of state discrimination for a set of mutually orthogonal pure states is trivial if one has access to the corresponding sharp (projection-valued) measurement, but what if we are restricted to an unsharp measurement? Given that any…

Quantum Physics · Physics 2021-03-03 Tom Bullock , Teiko Heinosaari