Abstract

Physical Review Letters (2003) 91 To be published.

Quantum Transmission of Atoms Through a Slab of Superfluid Helium

C.D.H. Williams and A.F.G. Wyatt

School of Physics, University of Exeter, Exeter, EX4 4QL (UK).

(Submitted 16 April 2003; Accepted 30 June 2003

We describe a measurement of the transmission probability of ⁴He atoms through a freely suspended slab of superfluid ⁴He at low temperatures. In our experiment the slab is realised by using an array of parallel cylindrical holes of diameter 51μm in a glass disc of thickness 190μm. By controlling the chemical potential, the holes can be made to fill or empty with liquid, and the surface curvature varied. We have measured the transmission of atom beams, generated by a thin-film heater and detected with a sensitive bolometer, through this structure. The results show that the dominant transmission channel is atom--R⁺ roton--atom with a probability ~0.12 and that R⁺ rotons can undergo total internal reflection at the free liquid surfaces.

Keywords: liquid helium, surfaces, quantum evaporation, quantum evaporation.
Reprint: doi:10.1103/PhysRevLett.91.085301