Physical Review Letters (2003) 91 To be published.
Quantum Transmission of Atoms Through a Slab of Superfluid Helium
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 4
atoms through a freely suspended slab of superfluid 4
He 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.