Junior Fellows Seminar: A C*-convex approach to the structure of quantum instruments

Speaker
Arghya Chongdar, Indian Statistical Institute Bangalore

Abstract
Completely positive (CP) instruments — CP map-valued measures — were introduced to capture the conditional state changes occurring during quantum processes. Viewing them as non-commutative analogues of joint probability measures, this talk explores the C*-extreme points of the set of instruments by deriving insights from their marginals. We revisit classical results on the extremality of joint distributions and lift them to the quantum setting. Finally, we present some Krein–Milman type approximation results for instruments.