Peter Frenkel, Lorand Eotvos University, Hungary

If shared randomness is available to the sender and the receiver, then any n-level quantum channel can be simulated by an n-state classical channel using classical states that are "at least as mixed" as the corresponding quantum states. This theorem is a generalization of an earlier result, which was joint with Mihaly Weiner and concerned the noiseless case. In mathematical terms, both results boil down to inequalities regarding mixed discriminants and eigenvalues of positive semidefinite matrices, but these are significantly deeper for the new, noisy result.

Recording of the talk