Resource theoretic efficacy of the single copy of a two-qubit entangled state in a sequential network

How best one can recycle a given quantum resource, mitigating the various difficulties involved in its preparation and preservation, is of considerable importance for ensuring efficient applications in quantum technology. Here we demonstrate quantitatively the resource theoretic advantage of reusing the single copy of a two-qubit entangled state towards information processing. To this end, we consider a scenario of sequential detection of the given entangled state by multiple independent observers on each of the two spatially separated wings. In particular, we consider equal numbers of sequential observers on the two wings. We first determine the upper bound on the number of observers who can detect entanglement employing suitable entanglement witness operators. In terms of the parameters characterizing the entanglement consumed and the robustness of measurements, we then compare the above scenario with the corresponding scenario involving the sharing of multiple copies of identical two-qubit states among the two wings. This reveals a clear resource theoretic advantage of recycling the single copy of a two-qubit entangled state.