Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 67: Quantum Information: Quantum Communication II
Q 67.8: Talk
Friday, March 27, 2015, 12:45–13:00, K/HS1
Renormalising entanglement distillation — Stephan Wäldchen1, •Janina Gertis2, Earl T. Campbell3, and Jens Eisert2 — 1Humboldt Universität Berlin, Germany — 2Freie Universität Berlin, Germany — 3University of Sheffield, United Kingdom
Entanglement distillation refers to the task of transforming a collection of weakly entangled pairs into fewer highly entangled ones. It is a core ingredient in quantum repeater protocols, needed to transmit entanglement over arbitrary distances in order to realise quantum key distribution schemes. Usually, it is assumed that the initial entangled pairs are i.i.d. distributed and uncorrelated with each other, an assumption that may be very much inappropriate in any entanglement generation process involving memory channels. Here, we introduce a framework that captures entanglement distillation in the presence of natural correlations arising from memory channels. Conceptually, we bring together ideas of condensed-matter physics - that of renormalisation - with those of local entanglement manipulation. Formally, we introduce ideas of tensor networks and matrix product operators to the context of entanglement distillation, and rigorously prove convergence to maximally entangled states in various meaningful settings, introducing notions of renormalisation of matrix-product operators.