Quantum entanglement and the arrow of time

​​In quantum mechanics, we appeal to decoherence as a process to explain the emergence of a quasi-classical order. Decoherence, whose origin lies in quantum entanglement, has no classical counterpart. Moreover, it is an irreversible process. This is a theoretical project in the foundations of physics that will explore the origin of irreversibility for an open quantum system (that is, time pointing in the direction of increasing entanglement) and whether it is similar to the origin of irreversibility in thermodynamics, namely that there is some measure of entanglement entropy for the universe that started off in a special initial state in the same way that Boltzmann’s thermodynamic entropy requires a ‘past hypothesis’. And since the quantum state of the universe is the only truly closed system (evolving according to the unitary dynamics of the Schrödinger equation), can we define an entanglement arrow of time for it even though it has no external environment to entangle with?

The project will require the student to learn about open quantum systems, the formalism of density matrices, master equations and different definitions of entropy. The work will also have a philosophical flavour and be in remote collaboration with a philosopher of physics based in the US.

Open to both UK and international candidates.

Up to 30% of our UKRI-funded studentships can be awarded to candidates paying international rate fees. Find out more about eligibility.

You will need to meet the minimum entry requirements for our Physics PhD programme.

​​Candidates need to have a good understanding of undergraduate quantum mechanics (essential). Some background in statistical mechanics would also be helpful.