Supervisors: Daniel Burgarth and Florian Mintert

QUANTUM CONTROL OF OPEN SYSTEMS

It is well established that the quantumness of nature allows machines that can do some tasks vastly better than classical ones. To this end, there is a large experimental effort to build quantum systems of ever growing size and precision. Control theory sits in quantum information and aims to bridge the divide between a physical system and an algorithm that we desire to perform on it; the two principle questions it asks are “What can we do with a system?” and “How can we do it?”

My research tackles both of these questions, especially in the case of realistic systems where unwanted interactions with the environment introduce noise. In [2] we investigated what operations can be done in the presence of such noise and introduced a set of no-go theorems based on geometric criteria. These conditions also show that some noise can be used to simulate others. The simulation question is directly addressed in [1], where we show how noise can be replicated with a Hamiltonian while using the smallest size quantum system possible.

Current work mostly focuses on asking if a quantum system could be used to perform some of the calculations required by control theory. A scheme that does this reduces what would have been an intractable problem to solve classically into a straightforward one for a quantum simulator, thereby upgrading it to a full quantum computer. Beyond the title of the project, research interests include what quantum information teaches us about fundamental quantum mechanics and thermodynamics. Outside of research I have been involved in teaching at an undergraduate and school level, and have taken part in organising a summer school and a conference.

[1] B. Dive, F. Mintert, and D. Burgarth, Phys. Rev. A 92, 032111 (2015)

[2] B. Dive, D. Burgarth, and F. Mintert, Phys. Rev. A 94, 021229 (2016)