Supervisors: Jiannis K. Pachos & Terry Rudolph
In quantum memories we are searching for physical states of matter that can robustly store quantum information. These would be analogous in a quantum computer to a magnetic hard disk in a classical computer.
In current computers bit values (0 or 1) can be stored in the net magnetic orientation (north up or north down) of a macroscopic magnetic domain. The thermodynamics of the magnet ensure that although individual atoms may change their orientation the whole magnet does not. Using quantum error correction theory quantum states (which are coherent combinations of 0 and 1) can also be stored in macroscopic degrees of freedom. For example the ground state degeneracy of the topological toric code. However there are some severe limitations to the robustness this provides. In general it is unknown if fully robust storage of quantum information can be achieved or if environmental noise will always destroy it.
In my PhD I have been working on analysing the robustness of different models of hypothetical quantum memories when they are coupled to realistic thermal environments. I am also currently studying some of the thermal properties of the topological Kitaev honeycomb model.
Quantum Memories at Finite Temperature, Benjamin J. Brown, Daniel Loss, Jiannis K. Pachos, Chris N. Self, James R. Wootton, arXiv:1411.6643, Nov 2014
Decay of a topological phase at finite temperature - University of Sheffield, 08/07/15
The ghostly line between good and bad science - Big Data & Psychics - Imperial College London, 23/07/14
Quantum memories based on the color code - Universität Basel, 02/05/14
Quantum memories based on the color code - University of Leeds, 12/11/13
QuICC Summer School (Imperial College London, 26-29 August 2013) “Reading out topologically protected quantum information”
Talked at "Amazing Quantum Worlds", Imperial College London, January 2013, May 2013.
Science Busking at Imperial Festival, Imperial College London, May 2013