Quantum correlations are essential for quantum information processing (QIP). Measurement-induced nonlocality (MIN) is a good measure of quantum correlation, and is favored for its conceptual implication and potential application. We investigated here the particular behaviors of the geometric and entropic measures of MIN in the two-qubit Heisenberg XY model and revealed the effects of anisotropic parameter γ and the external magnetic field B on them. Our results showed that both γ and B can serve as efficient controlling parameters for tuning MIN in the XY model.
The control of quantum correlations in a physical system is of practical importance. Nonlocal advantage of quantum coherence (NAQC) is a type of quantum correlation defined on the basis of quantum coherence. We present a comparative investigation of NAQC in the threespin Heisenberg model with periodic boundary conditions (PBCs) and topological boundary conditions (TBCs). The results show that while there is no NAQC in the absence of an external magnetic field, one can create a considerable NAQC by applying a nonuniform transverse magnetic field to the three spins. In particular, the NAQC is significantly improved for the model with TBCs compared to that with PBCs, and the regions of nonvanishing NAQC can also be extended. The model considered with TBC can therefore serve as a potential candidate for creating NAQC.
We examined measurement-induced nonlocality (MIN) of a central system for which every of the constituent qubit is embedded in its respective independent thermal reservoir. By introducing anisotropy to the Heisenberg XY interaction of the qubits, we showed that the strength of the MIN can be enhanced apparently. The anisotropy of the spin interaction can also be employed to generate MIN from the initial zero-MIN states. In the infinite-time limit, the steady-state MIN is independent of the initial states and is determined solely by the anisotropic parameter of the system and the decoherence factor of the thermal reservoir.
Quantum coherence underlies different forms of quantum correlations. We investigate the nonlocal advantage of quantum coherence (NAQC) for the thermal equilibrium states of both the spin-1/2 and the spin-1 Heisenberg XXZ models. By considering the NAQC formulated within two slightly different frameworks, we showed that their values can always be enhanced by tuning strength ∆ of the spin-exchange interaction along the z direction. The maximum achievable NAQC by tuning ∆ decreases with the increasing temperature T and there will be no NAQC when T is higher than a critical value. Moreover, both the NAQC and the critical temperature could be further noticeably increased by introducing the Dzyaloshinsky-Moriya interaction along either the z direction or the x direction to the considered spin models.
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