Theory of resources for systems that exchange quantum information

MATERA, J. M. ; EGLOFF, D.; THEURER, T; PLENIO, M. B.

Ciudad Autónoma de Buenos Aires

Congreso; Statphys 27; 2019

The theory of entanglement, one of the theoretical pillars of the field of quantum information, is formulated as a  Formal Resource Theory (FRT). A FRT provides a high-level description of a physical situation in terms of certain restrictions over the possible actions we can perform over certain experimental setup. A resource is then defined as a quantifiable property of the state of the system that allows overcoming these restrictions.For the case of entanglement (known as LOCC), it is assumed that any local operation (Local Operations) can be freely executed on any of the parts that compose the system, as well as exchange information by classical means (Classical Communication). On the other hand, operations that involve more than one party at a time, require that initially a resource be available: entanglement. However, there are situations that can not be described satisfactorily in this framework, due to the presence of quantum correlations other than entanglement. A paradigmatic example is that of two systems that exchange particles, which initially are not entangled with any of the parts, but due to remaining quantum correlations, are able to entangle the systems that they communicate. In this contribution, I am going to present a generalization of LOCC in which, unlike the standard one, communication channels are considered quantum systems. I will show how the resulting theory is deduced from the previous one in the regime in which the "wiring" that join the sub-systems present neither entanglement nor initial correlations. I will also show that this theory allows unifying, in a consistent and natural way, the theories of discord and quantum coherence with the theory of entanglement.