Entropic measures of quantum information

Abstract

Entropy has played a pivotal role in physics ever since its inception by Clausius in the early industrial age. Shannon ushered the concept into the information age by using it to describe fundamental limits of information processing, founding the field of information theory. Today, a fruitful interaction between information theory and physics is pushing our understanding of entropy forward. It has revealed, in particular, that no single notion of entropy suffices to capture all relevant properties of physical systems, making it necessary to consider a variety of entropic measures of quantum information, each with distinct features and uses. This review surveys these recent advances in a structured way, covering a comprehensive array of information measures, including Rényi and smooth entropies, together with their interrelations. Starting with a systematic characterization of entropies that motivates their definitions from natural physical principles, we discuss their applications ranging from quantum communication and cryptography to resource theories, thermodynamics, and many-body physics.