scholarly journals Experimental detection of non-local correlations using a local measurement-based hierarchy on an NMR quantum processor

2020 ◽  
Vol 74 (8) ◽  
Author(s):  
Amandeep Singh ◽  
Dileep Singh ◽  
Vaishali Gulati ◽  
Kavita Dorai ◽  
Arvind
Keyword(s):  
Local Measurement ◽  
Experimental Detection ◽  
Quantum Processor ◽  
Local Correlations ◽  
Non Local

scholarly journals Monotone Measures for Non-Local Correlations

2015 ◽  
Vol 61 (9) ◽  
pp. 5185-5208 ◽  
Author(s):  
Salman Beigi ◽  
Amin Gohari
Keyword(s):  
Local Correlations ◽  
Non Local

scholarly journals Quantum Correlation via Skew Information and Bell Function Beyond Entanglement in a Two-Qubit Heisenberg XYZ Model: Effect of the Phase Damping

2020 ◽  
Vol 10 (11) ◽  
pp. 3782 ◽  
Author(s):  
Abdel-Baset A. Mohamed ◽  
Ahmed Farouk ◽  
Mansour F. Yassen ◽  
Hichem Eleuch
Keyword(s):  
Sudden Change ◽  
Quantum Correlations ◽  
Physical Parameters ◽  
Phase Damping ◽  
Change Behavior ◽  
Skew Information ◽  
Local Correlations ◽  
Non Local ◽  
Moriya Interaction ◽  
Non Locality

In this paper, we analyze the dynamics of non-local correlations (NLCs) in an anisotropic two-qubit Heisenberg XYZ model under the effect of the phase damping. An analytical solution is obtained by applying a method based on the eigenstates and the eigenvalues of the Hamiltonian. It is observed that the generated NLCs are controlled by the Dzyaloshinskii–Moriya interaction, the purity indicator, the interaction with the environment, and the anisotropy. Furthermore, it is found that the quantum correlations, as well as the sudden death and sudden birth phenomena, depend on the considered physical parameters. In particular, the system presents a special correlation: the skew-information correlation. The log-negativity and the uncertainty-induced non-locality exhibit the sudden-change behavior. The purity of the initial states plays a crucial role on the generated nonlocal correlations. These correlations are sensitive to the DM interaction, anisotropy, and phase damping.

scholarly journals Superdeterministic hidden-variables models II: conspiracy

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200214
Author(s):  
Indrajit Sen ◽  
Antony Valentini
Keyword(s):  
Quantum Mechanics ◽  
Hidden Variables ◽  
Quantum Statistics ◽  
Fine Tuning ◽  
Previous Article ◽  
Local Measurement ◽  
Non Local ◽  
Further Development ◽  
Measurement Setting ◽  
Non Equilibrium

We prove that superdeterministic models of quantum mechanics are conspiratorial in a mathematically well-defined sense, by further development of the ideas presented in a previous article A . We consider a Bell scenario where, in each run and at each wing, the experimenter chooses one of N devices to determine the local measurement setting. We prove, without assuming any features of quantum statistics, that superdeterministic models of this scenario must have a finely tuned distribution of hidden variables. Specifically, fine-tuning is required so that the measurement statistics depend on the measurement settings but not on the details of how the settings are chosen. We quantify this as the overhead fine-tuning F of the model, and show that F  > 0 (corresponding to ‘fine-tuned’) for any N  > 1. The notion of fine-tuning assumes that arbitrary (‘non-equilibrium’) hidden-variables distributions are possible in principle. We also show how to quantify superdeterministic conspiracy without using non-equilibrium. This second approach is based on the fact that superdeterministic correlations can mimic actual signalling. We argue that an analogous situation occurs in equilibrium where, for every run, the devices that the hidden variables are correlated with are coincidentally the same as the devices in fact used. This results in extremely large superdeterministic correlations, which we quantify as a drop of an appropriately defined formal entropy. Non-local and retrocausal models turn out to be non-conspiratorial according to both approaches.

scholarly journals Multipartite Quantum Systems and Representations of Wreath Products

2020 ◽  
Vol 226 ◽  
pp. 02013
Author(s):  
Vladimir Kornyak
Keyword(s):  
Hilbert Space ◽  
Quantum Correlations ◽  
Wreath Products ◽  
Quantum Systems ◽  
Efficient Computation ◽  
Multipartite Quantum Systems ◽  
Irreducible Components ◽  
Local Correlations ◽  
Non Local ◽  
Multipartite System

The multipartite quantum systems are of particular interest for the study of such phenomena as entanglement and non-local correlations. The symmetry group of the whole multipartite system is the wreath product of the group acting in the “local” Hilbert space and the group of permutations of the constituents. The dimension of the Hilbert space of a multipartite system depends exponentially on the number of constituents, which leads to computational difficulties. We describe an algorithm for decomposing representations of wreath products into irreducible components. The C implementation of the algorithm copes with representations of dimensions in quadrillions. The program, in particular, builds irreducible invariant projectors in the Hilbert space of a multipartite system. The expressions for these projectors are tensor product polynomials. This structure is convenient for efficient computation of quantum correlations in multipartite systems with a large number of constituents.

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