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Quantum steering in a system consisting of a qubit coupled to a single-mode field is explored when classical-like measurements implemented by heterodyne detection schemes that collapse the state of the field on to a coherent state is…

Quantum Physics · Physics 2019-08-30 K. P. Athulya , Anil Shaji

We show that higher order inter-group covariances involving even number of qubits are necessarily positive semidefinite for N qubit separable states, which are completely symmetric under permutations of the qubits. This identification leads…

Quantum Physics · Physics 2009-11-13 A. R. Usha Devi , R. Prabhu , A. K. Rajagopal

It is shown that, despite strong nonlinearity, entanglement of formation of two-qubit state can be measured without prior state reconstruction. Collective measurements on small number of copies are provided that allow to determine quantum…

Quantum Physics · Physics 2007-05-23 Pawel Horodecki

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 study the separability of symmetric bipartite quantum states and show that a single correlation measurement is sufficient to detect the entanglement of any bipartite symmetric state with a non-positive partial transpose. We also discuss…

Quantum Physics · Physics 2010-02-24 Geza Toth , Otfried Gühne

We investigate quantum steering of an open quantum system by measurements on its environment in the framework of collision models. As an example we consider a coherently driven qubit dissipatively coupled to a bath. We construct local…

Quantum Physics · Physics 2018-03-23 Konstantin Beyer , Kimmo Luoma , Walter T. Strunz

As one of the most profound features of quantum mechanics, entanglement is a vital resource for quantum information processing. Inspired by the recent work on PT-moments and separablity [Phys. Rev. Lett. {\bf 127}, 060504 (2021)], we…

Quantum Physics · Physics 2024-02-21 Xiaofen Huang , Naihuan Jing

Quantum steering is a recently-defined form of quantum correlation which lies at the heart of quantum mechanics. In difference from other types of quantum correlations, quantum steering is inherently asymmetric, which implies that it could…

Quantum Physics · Physics 2022-02-25 Qiang Zeng , Jiangwei Shang , H. Chau Nguyen , Xiangdong Zhang

We present a new technique to reduce the expected number of measurements to declare an unknown quantum state as entangled. Our method is based on the geometric criterion and so requires only local Pauli measurements. Using concentration of…

Quantum Physics · Physics 2017-09-13 Bingjie Wang , Stephen Brierley

Protocols for testing or exploiting quantum correlations-such as entanglement, Bell nonlocality, and Einstein-Podolsky-Rosen steering- generally assume a common reference frame between two parties. Establishing such a frame is…

Quantum Physics · Physics 2018-09-12 Sabine Wollmann , Michael J. W. Hall , Raj B. Patel , Howard M. Wiseman , Geoff J. Pryde

The no-signalling principle is a fundamental assumption in Bell-inequality and quantum-steering experiments. Nonetheless, experimental imperfections can lead to apparent violations beyond those expected from finite-sample statistics. Here,…

This paper illustrates a direct connection between quantum steering and non-trivial preparation contextuality. In two party-two measurement per party-two outcomes per measurement $(2-2-2)$ Bell scenario, any argument of Bell nonlocality is…

Quantum Physics · Physics 2023-01-02 Prabuddha Roy , A. K. Pan

Einstein-Podolsky-Rosen (EPR) steering describes how different ensembles of quantum states can be remotely prepared by measuring one particle of an entangled pair. Here, we investigate quantum steering for single quantum d-dimensional…

Quantum Physics · Physics 2015-12-10 Che-Ming Li , Yueh-Nan Chen , Neill Lambert , Ching-Yi Chiu , Franco Nori

In this work, we will consider the star network scenario where the central party is trusted while all the edge parties (with a number of $n$) are untrusted. Network steering is defined with an $n$ local hidden state model which can be…

Quantum Physics · Physics 2024-04-18 Guangming Jiang , Xiaohua Wu , Tao Zhou

Quantum entanglement is a fundamental feature of quantum mechanics, yet certain entangled states that are unsteerable can be classically simulated in steering scenarios, making them unable to exhibit quantum steering. Despite their…

Quantum Physics · Physics 2025-11-05 Yujie Zhang , Jiaxuan Zhang , Eric Chitambar

Any two-qubit state can be faithfully represented by a steering ellipsoid inside the Bloch sphere, but not every ellipsoid inside the Bloch sphere corresponds to a two-qubit state. We give necessary and sufficient conditions for when the…

Quantum Physics · Physics 2015-03-23 Antony Milne , Sania Jevtic , David Jennings , Howard Wiseman , Terry Rudolph

Quantum steering is a perplexing feature at the heart of quantum mechanics that provides profound implications in understanding the nature of physical reality. On the other hand, the effect of relativistic features on quantum systems is…

Quantum Physics · Physics 2021-10-29 Yusef Maleki , Bahram Ahansaz , Kangle Li , Alireza Maleki

Quantum nonlocality and nonclassicality are two remarkable characteristics of quantum theory, and offer quantum advantages in some quantum information processing. Motivated by recent work on the interplay between nonclassicality quantified…

Quantum Physics · Physics 2024-10-16 youneng Guo , Xiangjun Chen , huping Peng , qinglong Tian

Within the framework of quantum refereed steering games, quantum steerability can be certified without any assumption on the underlying state nor the measurements involved. Such a scheme is termed the measurement-device-independent (MDI)…

In [\href{http://www.sciencedirect.com/science/article/pii/037596019290711T}{Phys. Lett. A {\bf 166}, 293 (1992)}] Popescu characterized nonlocality of pure $n$-partite entangled systems by studying bipartite violation of local realism when…