Approximate entropy accumulationConfirmed

by Frédéric Dupuis (University of Montreal)

Wednesday May 28, 2025, 11:00 a.m. → 12:30 p.m. America/Toronto

PI/4-405 - Bob Room (Perimeter Institute for Theoretical Physics)

The entropy accumulation theorem (EAT) allows us to lower

bound the min-entropy of a state that can be generated by a chain of

quantum channels satisfying a Markov chain condition, and can be used to

prove the security of QKD protocols, including device-independent ones.

However, one of its drawbacks is that it only applies to states with a

fairly rigid structure; in particular, the Markov chain condition must

be satisfied exactly. What happens when we relax this assumption by

allowing the required structure to be satisfies only approximately? Does

doing so lead to interesting applications? We answer both questions by

the affirmative: we present two flavours of approximate EAT, and show

that it can be used to prove the security of parallel device-independent

QKD, and to analyze QKD protocols under source correlations. Along the

way, we will introduce the concept of "approximation chain" which

underpins the new results.

 

This is joint work with Ashutosh Marwah; the talk will cover material

from 2412.06723, 2402.12346, and 2308.11736.