Single Quantum Electronics on Helium
It is possible for the surface of liquid 4He to support electrons. Below 2.2 K the liquid is in a quantum mechanical ground state known as a superfluid, the surface of the liquid is the most perfect material support known. Attracted by the image of their own charge in the dielectric mirror that is the Helium, the electrons ‘float’ some tens of nanometres above the surface of the liquid in a set of quantum states that vary in energy with vertical distance from the surface, in a 1D analogue of the Rydberg states of the hydrogen atom.
Horizontally, many electrons will form a floating electronic film, with each individual electron repelling its neighbours, leading to the most perfect two dimensional electron gas known, it exhibits both fluid and solid behaviour, depending on electron density. In this project metallic and superconducting electrodes submerged just below the surface are used to isolate and manipulate single electrons on the surface. With the electrons residing in potential wells formed by the electrodes, the horizontal confinement leads to a refined set of quantum levels. By controlling the electrode potentials we may move electrons one by one from one well to another and by precisely applying radiofrequency photons we may manipulate the quantum state of the electron. Electron state detection is performed via a superconducting single electron transistor beneath the Helium surface. We plan a series of measurements of single electron quantum tunnelling through and thermal activation over the barriers, RF spectroscopy of the vertical states for multiple and single electrons, quantum manipulation of single electron states, measurement of the decoherence time of the electron state and characterisation of the quantum state readout, to name just a few.
The PhD project will include training in nanofabrication, cryogenics and radiofrequency technology and will appeal to candidates with interests in condensed matter physics, nanotechnology and quantum systems.
 G. Papageorgiou, P. Glasson, K. Harrabi, V.Antonov, E.Collin, P.Fozooni, P.G.Frayne, D.G.Rees, Y.Mukharsky and M.J.Lea, App. Phys. Lett. 86, 153106 (2005).
For further information contact Dr Phil Meeson.