Observation of correlations in tunneling of surface-state electrons

Abstract

We measured the escape rates of surface-state electrons from an electron layer confined at the liquidheliumvacuum interface in the temperature range of 30 -450 mK, for densities (0.02 -2.2) X10' cm We compared the measured escape rates with calculated tunneling rates in a model where the interactions between the escaping electron and the other electrons are described by an effective single-particle potential. Below 200 mK the escape rates were temperature independent. The single-particle rates were enhanced exponentially as the density was increased up to a critical density n, . In this regime the calculated and measured rates were in good agreement. At n, we observe a one order of magnitude steep rise and the time development of density becomes extremely nonlinear. We show that this nonlinearity can be explained by the electron impact excitation of helium atoms on the walls of the cell. As the barrier is raised so that the escape rates decrease below 5.0X 10 sec ', a new mechanism seems to dominate the escape and the rates become very weakly density and external field dependent. Thermally activated escape was observed above 250 rnK and the activation energies were in good agreement with the calculated values.

Surface Fluctuations of Normal and SuperfluidH3eProbed by Wigner Solid Dynamics

“…The measurements were performed at the rf power of 281 dBm, which corresponds to the power absorption of 0.1 pW by the SE. If the power is increased far above this level, the frequency of the resonance starts to decrease and the shape becomes sharper, consistent with the result obtained by Yucel et al [11].…”

Ripplonic Lamb Shift for Electrons on Liquid Helium

“…On the other hand, it has been known that the electrons are also coupled to a bosonic field, the capillary waves on the surface of helium (ripplons), and that this coupling affects the electron energy spectrum [20][21][22][23][24]. The importance of this effect was demonstrated in explaining the Wigner crystallization [8,25] and through cyclotron-resonance measurements [26].In terms of the coupling to a bosonic field, electrons on helium are a close condensed-matter analog of systems studied in quantum electrodynamics. The known form of the coupling [27] and the possibility to control it and to study the interplay of this coupling with the manyelectron effects make the system particularly attractive.…”

Ripplonic Lamb shift for electrons on liquid helium

“…On the other hand, it has been known that the electrons are also coupled to a bosonic field, the capillary waves on the surface of helium (ripplons), and that this coupling affects the electron energy spectrum [20][21][22][23][24]. The importance of this effect was demonstrated in explaining the Wigner crystallization [8,25] and through cyclotron-resonance measurements [26].…”