Information and Physics

Our research is rooted in the insight that information and physics are closely intertwined: First, “information is physical” (Landauer), i.e., any information representation, treatment, or transmission process is ultimately physical and should be understood as such. Second, the standpoint of information sometimes allows us for understanding physical laws — particularly from quantum theory or thermodynamics — better and more deeply. In the proposed project, we plan to start from here and investigate questions in the intersection of quantum physics, information theory, cryptography, and communication complexity. Our goal hereby will, generally, be two-fold: On the one hand, we exploit the use of physical laws and phenomena for information processing, i.e., for realizing tasks (e.g., achieve levels of security) impossible otherwise. On the other, we plan to study quantum phenomena such as entanglement or non-locality from the point of view of information with the goal of obtaining a deeper understanding. In particular, we propose four sub-projects devoted to the following subjects and questions:1. Investigate the possibility of realizing information-theoretically secure cryptography based on physical assumptions and primitives. More specifically, we are interested in the realization of secret-key agreement, authentication, bit commitment, oblivious transfer, and general two- and multi-party computation from quantum channels, entanglement, non-local correlations, as well as physical unclonable functions.2. Determine the communication complexity of non-local correlations and quantum-physical behavior.3. Get a deeper understanding for the information principles that characterize quantum theory. We plan to describe, classify, characterize, and delimit quantum-physical correlations in terms of information theory.4. Understand the information-theoretic consequences of the impossibility to explain quantum theory in terms of hidden variables. What is this fact useful for — besides device-independent key agreement? What information or communication models (possible explanations) for quantum-physical behavior are compatible with the nature of non-local correlations, and which are not?We expect the outcomes to have an impact in all fields involved — as it has oftenbeen the case in our research. More precisely, it lies in the nature of the proposed project that engineering characteristics and methodology — “what can we do efficiently?” — are combined with science aspects — “can we understand the underlying phenomena better?”.