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In this paper, we consider the problem of unambiguous discrimination between a set of mixed quantum states. We first divide the density matrix of each mixed state into two parts by the fact that it comes from ensemble of pure quantum…

Quantum Physics · Physics 2007-05-23 Chi Zhang , Yuan Feng , Ming Sheng Ying

Implementing a qubit quantum computer in continuous-variable systems conventionally requires the engineering of specific interactions according to the encoding basis states. In this work, we present a unified formalism to conduct universal…

Quantum Physics · Physics 2016-09-06 Hoi-Kwan Lau , Martin B. Plenio

The required set of operations for universal continuous-variable quantum computation can be divided into two primary categories: Gaussian and non-Gaussian operations. Furthermore, any Gaussian operation can be decomposed as a sequence of…

Quantum Physics · Physics 2020-02-12 Kunal Sharma , Mark M. Wilde

We study optimal perfect distinguishability between a unitary and a general quantum operation. In 2-dimensional case we provide a simple sufficient and necessary condition for sequential perfect distinguishability and an analytical formula…

Quantum Physics · Physics 2010-10-13 Cheng Lu , Jianxin Chen , Runyao Duan

We analyze the optimal unambiguous discrimination of two arbitrary mixed quantum states. We show that the optimal measurement is unique and we present this optimal measurement for the case where the rank of the density operator of one of…

Quantum Physics · Physics 2010-03-22 M. Kleinmann , H. Kampermann , D. Bruss

We consider the problem of designing an optimal quantum detector that distinguishes unambiguously between a collection of mixed quantum states. Using arguments of duality in vector space optimization, we derive necessary and sufficient…

Quantum Physics · Physics 2009-11-10 Yonina C. Eldar , Mihailo Stojnic , Babak Hassibi

In this article, we study the problem of comparing mixed quantum states: given $n$ unknown mixed quantum states, can one determine whether they are identical or not with an unambiguous quantum measurement? We first study universal…

Quantum Physics · Physics 2015-05-18 Shengshi Pang , Shengjun Wu

We address the problem of unambiguous discrimination and identification among quantum observables. We set a general framework and investigate in details the case of qubit observables. In particular, we show that perfect discrimination with…

Quantum Physics · Physics 2008-07-15 Mario Ziman , Teiko Heinosaari

Generalized quantum measurements identifying non-orthogonal states without ambiguity often play an indispensable role in various quantum applications. For such unambiguous state discrimination scenario, we have a finite probability of…

Quantum Physics · Physics 2021-04-16 Shuro Izumi , Jonas S. Neergaard-Nielsen , Ulrik L. Andersen

Distinguishing physical processes is one of the fundamental problems in quantum physics. Although distinguishability of quantum preparations and quantum channels have been studied considerably, distinguishability of quantum measurements…

Quantum Physics · Physics 2021-04-13 Chandan Datta , Tanmoy Biswas , Debashis Saha , Remigiusz Augusiak

We consider N quantum systems initially prepared in pure states and address the problem of unambiguously comparing them. One may ask whether or not all $N$ systems are in the same state. Alternatively, one may ask whether or not the states…

Quantum Physics · Physics 2014-11-18 Anthony Chefles , Erika Andersson , Igor Jex

We study the distinguishability of multipartite quantum states by separable operations. We first present a necessary and sufficient condition for a finite set of orthogonal quantum states to be distinguishable by separable operations. An…

Quantum Physics · Physics 2009-06-25 Runyao Duan , Yuan Feng , Yu Xin , Mingsheng Ying

To effectively utilize quantum incompatibility as a resource in quantum information processing, it is crucial to evaluate how incompatible a set of devices is. In this study, we propose an ordering to compare incompatibility and reveal its…

Quantum Physics · Physics 2026-01-09 Kensei Torii , Ryo Takakura , Ryotaro Imamura

Electron transport in realistic physical and chemical systems often involves the non-trivial exchange of energy with a large environment, requiring the definition and treatment of open quantum systems. Because the time evolution of an open…

We address the problem of discriminating with minimal error probability two given quantum operations. We show that the use of entangled input states generally improves the discrimination. For Pauli channels we provide a complete comparison…

Quantum Physics · Physics 2009-11-11 Massimiliano F. Sacchi

The ability to uniquely identify a quantum state is integral to quantum science, but for non-orthogonal states, quantum mechanics precludes deterministic, error-free discrimination. However, using the non-deterministic protocol of…

Quantum Physics · Physics 2014-08-04 Megan Agnew , Eliot Bolduc , Kevin J. Resch , Sonja Franke-Arnold , Jonathan Leach

The problem of discriminating the state of a quantum system among a number of hypothetical states is usually addressed under the assumption that one has perfect knowledge of the possible states of the system. In this thesis, I analyze the…

Quantum Physics · Physics 2014-07-18 Gael Sentís

We demonstrate an implementation of unambiguous state discrimination of two equally probable single-qubit states via a one-dimensional photonic quantum walk experimentally. Furthermore we experimentally realize a quantum walk algorithm for…

Quantum Physics · Physics 2014-10-10 Zhihao Bian , Rong Zhang , Hao Qin , Xiang Zhan , Jian Li , Peng Xue

It is a central fact in quantum mechanics that non-orthogonal states cannot be distinguished perfectly. This property ensures the security of quantum key distribution. It is therefore an important task in quantum communication to design and…

Quantum Physics · Physics 2023-11-27 Lorcan O. Conlon , Falk Eilenberger , Ping Koy Lam , Syed M. Assad

We study an optimized measurement that discriminates two mixed quantum states with maximum confidence for each conclusive result, thereby keeping the overall probability of inconclusive results as small as possible. When the rank of the…

Quantum Physics · Physics 2009-11-13 Ulrike Herzog