Witnessing network steerability of every bipartite entangled state without inputs

Shubhayan Sarkar

Published 2024-06-17Version 1

Entanglement and nonlocality are key resources for most of the quantum information protocols. It is well-established now that every entangled state is nonlocal with respect to semi-quantum games. However, there is a lack of witnesses that can used to observe any form of nonlocality of every entangled state. In this work, we focus on the swap-steering scenario without inputs and find linear witnesses of network steerability corresponding to any negative partial transpose (NPT) bipartite state and a large class of bipartite states that violate the computable cross-norm (CCN) criterion. Furthermore, by considering that the trusted party can perform tomography of the incoming subsystems, we construct linear inequalities to witness swap-steerability of every bipartite entangled state. Consequently, for every bipartite entangled state one can now observe a form of quantum nonlocality.