Applied Mathematics PhD comprehensive examination | Robert Jonsson

MC 5136

Speaker

Robert Jonsson, Department of Applied Mathematics, University of Waterloo

Title

Relativistic Quantum Communications

Abstract

Since their discovery, General Relativity and Quantum Theory revolutionized not only our view of the world but by means of the digital revolution, in fact, our everyday life as well. However the problem of unifying these two successful theories remains unsolved for over half a century by now.

In recent years an approach called Relativistic Quantum Information has produced many interesting results by connecting quantum and relativistic effects through Information Theory. Following this idea, we study the communication between simple quantum systems that are connected via quantum fields, so called Unruh-DeWitt detectors, in relativistic settings. This model may serve as a general toy model, e.g., for signalling between atoms via the exchange of photons in curved spacetimes.

In this talk, we discuss the general structure of the quantum channel between two Unruh-DeWitt detectors. We show why Alice should not try to encode messages to Bob using energy eigenstates of her detector, but why she should use superposition states instead. Furthermore, we discuss recent work, where the quantum channel was applied to quantum field in cavities. Using causality arguments the fidelity of approximative methods, that only use a finite number of modes, was investigated in relativistic scenarios.