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We consider the class of protocols that can be implemented by local quantum operations and classical communication (LOCC) between two parties. In particular, we focus on the task of discriminating a known set of quantum states by LOCC.…

Quantum Physics · Physics 2013-10-09 Andrew M. Childs , Debbie Leung , Laura Mancinska , Maris Ozols

An orthonormal basis consisting of unentangled (pure tensor) elements in a tensor product of Hilbert spaces is an Unentangled Orthogonal Basis (UOB). In general, for $n$ qubits, we prove that in its natural structure as a real variety, the…

Quantum Physics · Physics 2016-08-08 Jiri Lebl , Asif Shakeel , Nolan Wallach

A set of quantum states is said to be antidistinguishable if, upon being given a randomly chosen state, it is possible to identify a state that the system was definitively not prepared in. In this work, we begin with a study of quantum…

Quantum Physics · Physics 2026-05-12 Biswadeep Chatterjee , Tathagata Gupta , Pratik Ghosal , Samrat Sen

A set of orthogonal multipartite quantum states are called (distinguishability-based) genuinely nonlocal if they are locally indistinguishable across any bipartition of the subsystems. In this work, we consider the problem of constructing…

Quantum Physics · Physics 2024-01-31 Zong-Xing Xiong , Yongli Zhang , Mao-Sheng Li , Lvzhou Li

Based on the conviction of switching information from locally accessible to locally hidden environs, the concept of hidden nonlocality activation has recently been highlighted by Bandyopadhyay et al. in [Phys. Rev. A 104, L050201 (2021)].…

Quantum Physics · Physics 2025-08-21 Subrata Bera , Atanu Bhunia , Indranil Biswas , Indrani Chattopadhyay , Debasis Sarkar

An ensemble of product states is said to exhibit "quantum nonlocality without entanglement" if the states cannot be optimally discriminated by local operations and classical communication (LOCC). We show that this property can depend on the…

Quantum Physics · Physics 2025-06-26 Shayeef Murshid , Tathagata Gupta , Vincent Russo , Somshubhro Bandyopadhyay

The structure of quantum theory assures the discrimination of any possible orthogonal set of states. However, the scenario becomes highly nontrivial in the limited measurement setting and leads to different classes of impossibility, viz.,…

We study the role of entanglement and non-locality in quantum protocols that make use of systems of identical particles. Unlike in the case of distinguishable particles, the notions of entanglement and non-locality for systems whose…

Quantum Physics · Physics 2021-05-24 Fabio Benatti , Roberto Floreanini , Ugo Marzolino

We explore entanglement as a resource to distinguish locally indistinguishable orthogonal quantum states. Specifically, we consider sets which contain states from an unextendible product basis along with a pure entangled state. We establish…

Quantum Physics · Physics 2025-09-30 Abhay Srivastav , Saronath Halder

The unextendible product bases (UPBs) are interesting members from the family of orthogonal product states. In this paper, we investigate the construction of 3-qubit UPB with strong nonlocality of different sizes. First, a UPB set in…

Quantum Physics · Physics 2021-06-24 Bichen Che , Zhao Dou , Min Lei , Yixian Yang

Now, the known ensembles of orthogonal states which are distinguishable by local operators and classical communication (LOCC) satisfy the condition that the sum of Schmidit numbers of the orthogonal states is not bigger than the dimensions…

Quantum Physics · Physics 2007-05-23 Ping-Xing Chen , Wei Jiang , Zheng-Wei Zhou , Guang-Can Guo

Non-locality without entanglement is a rather counter-intuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is…

Quantum Physics · Physics 2017-03-08 Sarah Croke , Stephen M Barnett

The ontological model framework for an operational theory has generated much interest in recent years. The debate concerning reality of quantum states has been made more precise in this framework. With the introduction of generalized notion…

Quantum Physics · Physics 2015-10-06 Manik Banik , Some Sankar Bhattacharya , Sujit K Choudhary , Amit Mukherjee , Arup Roy

Gauging a global symmetry of a system amounts to introducing new degrees of freedom whose transformation rule makes the overall system observe a local symmetry. In quantum systems there can be obstructions to gauging a global symmetry. When…

Quantum Physics · Physics 2023-03-01 José Garre Rubio , Ilya Kull

Quantum information is nonlocal in the sense that local measurements on a composite quantum system, prepared in one of many mutually orthogonal states, may not reveal in which state the system was prepared. It is shown that in the many copy…

Quantum Physics · Physics 2015-05-28 Somshubhro Bandyopadhyay

Any set of states which cannot be perfectly distinguished by local operations and classical communication (LOCC) alone, can always be locally distinguished using quantum teleportation with enough entanglement resource. However, in quantum…

Quantum Physics · Physics 2020-02-12 Zhi-Chao Zhang , Xia Wu , Xiangdong Zhang

We analyze entanglement and nonlocal properties of the convex set of symmetric $N$-qubits states which are diagonal in the Dicke basis. First, we demonstrate that within this set, positivity of partial transposition (PPT) is necessary and…

Quantum Physics · Physics 2017-05-03 Ruben Quesada , Swapan Rana , Anna Sanpera

Nonlocality is arguably one of the most fundamental and counterintuitive aspects of quantum theory. Nonlocal correlations could, however, be even more nonlocal than quantum theory allows, while still complying with basic physical principles…

Quantum Physics · Physics 2014-03-17 A. B. Sainz , T. Fritz , R. Augusiak , J. Bohr Brask , R. Chaves , A. Leverrier , A. Acín

The nonlocal set has received wide attention over recent years. Shortly before, Li and Wang arXiv:2202.09034 proposed the concept of a locally stable set: the only possible orthogonality preserving measurement on each subsystem is trivial.…

Quantum Physics · Physics 2023-07-18 Hai-Qing Cao , Mao-Sheng Li , Hui-Juan Zuo

Nonlocality exhibited by ensembles of composite quantum states, wherein local operations and classical communication (LOCC) yield suboptimal discrimination probabilities compared to global strategies, is one of the striking nonclassical…

Quantum Physics · Physics 2025-12-02 Samrat Sen