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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

We define and fully characterize the witnesses based on second moments detecting steering in Gaussian states by means of Gaussian measurements. All such tests, which arise from linear combination of variances or second moments of canonical…

Quantum Physics · Physics 2023-04-25 Tatiana Mihaescu , Hermann Kampermann , Aurelian Isar , Dagmar Bruß

We introduce entanglement witnesses for spin ensembles which detect genuine multipartite entanglement using only measurements of the total angular momentum. States that are missed by most other angular-momentum-based witnesses for spin…

Quantum Physics · Physics 2024-04-02 Khoi-Nguyen Huynh-Vu , Lin Htoo Zaw , Valerio Scarani

The development of large-scale quantum networks promises to bring a multitude of technological applications as well as shed light on foundational topics, such as quantum nonlocality. It is particularly interesting to consider scenarios…

Quantum Physics · Physics 2021-11-09 Benjamin D. M. Jones , Ivan Šupić , Roope Uola , Nicolas Brunner , Paul Skrzypczyk

The effect of quantum steering describes a possible action at a distance via local measurements. Whereas many attempts on characterizing steerability have been pursued, answering the question as to whether a given state is steerable or not…

Quantum Physics · Physics 2018-11-13 Ana C. S. Costa , Roope Uola , Otfried Gühne

Bell nonlocality between distant quantum systems---i.e., joint correlations which violate a Bell inequality---can be verified without trusting the measurement devices used, nor those performing the measurements. This leads to…

Quantum Physics · Physics 2015-01-16 Sacha Kocsis , Michael J. W. Hall , Adam J. Bennet , Dylan J. Saunders , G. J. Pryde

Entanglement detection typically relies on linear inequalities for mean values of certain observables (entanglement witnesses), where violation indicates entanglement. We provide a general method to improve any of these inequalities for…

Quantum Physics · Physics 2007-05-23 Otfried Gühne , Norbert Lütkenhaus

Superunsteerability is a particular kind of spatial quantum correlation that can be observed in a steering scenario in the presence of limited shared randomness. In this work, we define an experimentally measurable quantity in a steering…

Quantum Physics · Physics 2023-07-19 Chellasamy Jebarathinam , Debarshi Das

Nonlocal correlations arising from measurements on tripartite entangled states can be classified into two groups, one genuinely $3-$way nonlocal and other local with respect to some bipartition. Still, whether a genuinely tripartite…

Quantum Physics · Physics 2016-11-15 Biswajit Paul , Kaushiki Mukherjee , Debasis Sarkar

Quantum nonlocality is a kind of significant quantum correlation that is stronger than quantum entanglement and EPR steering. The standard tripartite nonlocality can be detected by the violation of the Mermin inequality. By using local…

Quantum Physics · Physics 2022-05-24 Qiao-Qiao Lv , Jin-Min Liang , Zhi-Xi Wang , Shao-Ming Fei

The phenomenon of quantum steering in bipartite quantum systems can be reduced to the question whether or not the first party can perform measurements such that the conditional states on the second party can be explained by a local hidden…

Quantum Physics · Physics 2020-05-06 H. Chau Nguyen , Otfried Gühne

The study of stronger-than-quantum effects is a fruitful line of research that provides valuable insight into quantum theory. Unfortunately, traditional bipartite steering scenarios can always be explained by quantum theory. Here we show…

Quantum Physics · Physics 2020-08-05 Ana Belén Sainz , Matty J. Hoban , Paul Skrzypczyk , Leandro Aolita

Genuine multipartite nonlocality is a salient feature of quantum systems, empowering the security of multi-party device independent cryptographic protocols. Given a correlation, characterizing and detecting genuineness have been subjected…

Quantum Physics · Physics 2015-07-28 Some Sankar Bhattacharya , Arup Roy , Amit Mukherjee , Ramij Rahaman

Quantum steering is the phenomenon whereby one party (Alice) proves entanglement by "steering'' the system of another party (Bob) into distinct ensembles of states, by performing different measurements on her subsystem. Here, we investigate…

Quantum Physics · Physics 2024-04-04 Qiu-Cheng Song , Travis J. Baker , Howard M. Wiseman

Within the hierarchy of inseparable quantum correlations, Einstein-Podolsky-Rosen steering is distinguished from both entanglement and Bell nonlocality by its asymmetry -- there exist conditions where the steering phenomenon changes from…

Quantum Physics · Physics 2016-04-27 Sabine Wollmann , Nathan Walk , Adam J. Bennet , Howard M. Wiseman , G. J. Pryde

We investigate the connection between steering and contextuality in general probabilistic theories. We show that for a class of bipartite states the steerability of the state by given set of measurements is equivalent to non-existence of…

Quantum Physics · Physics 2022-09-26 Martin Plávala

Einstein-Podolsky-Rosen (EPR) steering is a form of quantum nonlocality which is intermediate between entanglement and Bell nonlocality. EPR steering is a resource for quantum key distribution that is device independent on only one side in…

Quantum Physics · Physics 2016-09-29 C. Jebaratnam

The state of a quantum system may be steered towards a predesignated target state, employing a sequence of weak $\textit{blind}$ measurements (where the detector's readouts are traced out). Here we analyze the steering of a two-level system…

Quantum Physics · Physics 2022-01-19 Parveen Kumar , Kyrylo Snizhko , Yuval Gefen , Bernd Rosenow

In the last few years, several criteria to identify Eistein-Podolski-Rosen steering have been proposed and experimentally implemented. On the operational side, however, the evaluation of the steerability degree of a given state has shown to…

Quantum Physics · Physics 2016-03-09 A. C. S. Costa , R. M. Angelo

We investigate entanglement detection when the local measurements only nearly correspond to those intended. This corresponds to a scenario in which measurement devices are not perfectly controlled, but nevertheless operate with bounded…

Quantum Physics · Physics 2022-06-22 Simon Morelli , Hayata Yamasaki , Marcus Huber , Armin Tavakoli