Experiments with Electrons on Helium

The P.I. proposes exploratory experiments, using a new and potentially very powerful measurement technique, to elucidate the phenomenon of macroscopic quantum tunneling. The role of many- body effects and the influence of an external magnetic field will be explored. The system to be studied comprises a layer of electrons suspended above a surface of liquid helium. A modest electric field applied perpendicularly to the electron sheet forms an energy barrier that leaves an electron in a metastable state from which it can escape by activation over the barrier or by tunneling through it. The wide range of control over experimental parameters that is here available makes this an ideal system for study. To monitor the tunneling rates, some new techniques will be tried, allowing direct measurement of the electron temperature and density, and of the external perturbations such as electric field and excitations of the He surface ("ripplons").