Quantum resource theories

Quantum resource theories (QRTs) offer a highly versatile and powerful\nframework for studying different phenomena in quantum physics. From quantum\nentanglement to quantum computation, resource theories can be used to quantify\na desirable quantum effect, develop new protocols for its detection, and\nidentify processes that optimize its use for a given application. Particularly,\nQRTs revolutionize the way we think about familiar properties of physical\nsystems like entanglement, elevating them from just being interesting from a\nfundamental point of view to being useful in performing practical tasks. The\nbasic methodology of a general QRT involves partitioning all quantum states\ninto two groups, one consisting of free states and the other consisting of\nresource states. Accompanying the set of free states is a collection of free\nquantum operations arising from natural restrictions on physical systems, and\nthat consists of all the physical processes allowed by the resource theory and\nwhich acts invariantly on the set of free states. The QRT then studies what\ninformation processing tasks become possible using the restricted operations.\nDespite the large degree of freedom in how one defines the free states and free\noperations, unexpected similarities emerge among different QRTs in terms of\nresource measures and resource convertibility. As a result, objects that appear\nquite distinct on the surface, such as entanglement and quantum reference\nframes, appear to have great similarity on a deeper structural level. In this\narticle we review the general framework of a quantum resource theory, focusing\non common structural features, operational tasks, and resource measures. To\nillustrate these concepts, an overview is provided on some of the more commonly\nstudied QRTs in the literature.\n