Środowiskowe Seminarium z Informacji i Technologii Kwantowych

The theory of the asymptotic manipulation of pure bipartite quantumsystems can be considered completely understood: The rates at whichbipartite entangled states can be asymptotically transformed intoeach other are fully determined by a single number each, the respectiveentanglement entropy. In the multi-partite setting, similar questionsof the optimally achievable rates of transforming one pure state intoanother are notoriously open. This seems particularly unfortunatein the light of the revived interest in such questions due to theperspective of experimentally realizing multi-partite quantum networks.In this work, we report substantial progress by deriving surprisinglysimple upper and lower bounds on the rates that can be achieved inasymptotic multi-partite entanglement transformations. These boundsare based on ideas of entanglement combing and state merging. We identify cases where the bounds coincide and hence provide the exact rates. As an example, we bound rates at which resource states for the cryptographic scheme of quantum secret sharing can be distilled from arbitrary pure tripartite quantum states, providing further scope for quantum internet applications beyond point-to-point.