Abstract
The phenomenon of nonlocality without entanglement (NLWE) arises in discriminating multi-party quantum separable states. Recently, it has been found that the post-measurement information about the prepared subensemble can lock or unlock NLWE in minimum-error discrimination of non-orthogonal separable states. Thus It is natural to ask whether the availability of the post-measurement information can influence on the occurrence of NLWE even in other state-discrimination strategies. Here, we show that the post-measurement information can be used to lock as well as unlock the occurrence of NLWE in terms of optimal unambiguous discrimination. Our results can provide a useful application for hiding or sharing information based on non-orthogonal separable states.
Highlights
The phenomenon of nonlocality without entanglement (NLWE) arises in discriminating multi-party quantum separable states
As a main result of this paper, we provide a quantum state ensemble consisting of four two-qubit product states and show the occurrence of NLWE in terms of optimal unambiguous discrimination
We have shown that the post-measurement information about the prepared subensemble can lock or unlock NLWE in terms of optimal unambiguous discrimination
Summary
The phenomenon of nonlocality without entanglement (NLWE) arises in discriminating multi-party quantum separable states. It has been found that the post-measurement information about the prepared subensemble can lock or unlock NLWE in minimum-error discrimination of non-orthogonal separable states. In optimal discriminations with the post-measurement information about the prepared subensemble, the NLWE phenomenon arises when the globally optimal discrimination cannot be implemented by LOCC with the help of post-measurement information. It was shown that the availability of postmeasurement information can lock or unlock NLWE in terms of minimum-error d iscrimination[31], it is natural to ask whether the post-measurement information affects the occurrence of NLWE in terms of statediscrimination strategies other than minimum-error discrimination. We first provide an ensemble of two-qubit product states having NLWE in terms of optimal unambiguous discrimination, and show that the availability of post-measurement information about the prepared subensemble vanishes the occurrence of NLWE, locking NLWE in terms of optimal unambiguous discrimination by post-measurement information. We further provide another ensemble of two-qubit product state that does not have NLWE in terms of optimal unambiguous discrimination, and show that NLWE in the optimal unambiguous discrimination can be released
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