Quantum Information Seminar Series: Graeme Smith

Abstract:

While quantum information theory is typically studied in the finite-dimensional regime, many real-world physical channels are best described in terms of continuous variables.  The simplest such channels are gaussian bosonic channels, which result from a quadratic unitary interaction between bosonic transmission modes and an inaccessible environment in the vacuum state.  This class includes good approximations of most realistic optical channels.  I'll review the theory of quantum information for continuous variables, then show that the set of bosonic gaussian channels is sufficiently rich to allow superactivation: there are pairs of channels, neither of which can transmit quantum information on its own, that can nevertheless be used together for reliable quantum communication.