Crypto Reading Group on quantum computing | Quantum Information Theory

Abstract: Pure quantum states describe systems whose preparation is known exactly, but realistic quantum information often involves uncertainty, inaccessible subsystems, and interactions with the environment. In this talk, we introduce density operators as a general framework encompassing both pure and mixed states. We then discuss quantum channels, which model physical transformations and common forms of noise affecting quantum systems. Finally, we introduce classical and quantum entropy as measures of uncertainty and information, and explain how these ideas provide basic intuition for quantum cryptographic security.