Allowed and forbidden bipartite correlations from thermal states.

Abstract

The strong connection between correlations and quantum thermodynamics raises a natural question about the preparation of correlated quantum states from two copies of a thermal qubit. In this work we study the specific forms of allowed and forbidden bipartite correlations. As a consequence, we extend the result to separable but not absolutely separable class of product states. Preparation of a general form of entanglement from arbitrary thermal qubits is studied and, as an application, we propose a strategy to establish desired entanglement between two distant parties. The threshold temperature to produce entanglement from two copies of a thermal qubit has also been discussed from the resource theoretic perspective, which ensures that the bound on the temperature can be superseded with the help of a resource state. A dimension dependent upper bound on the temperature is derived, below which two copies of any d-dimensional thermal state can be entangled in 2×d dimensions.