Recent experiments on superfluidity

J C Davis, J. D. Close, R. Zieve +1 more

This paper provides a brief description of recent experiments measuring the fluid circulation in 3He. In the B phase, the circulation around a 16 ~m diameter wire is found to be quantized in units of h/2m~. Possible future experiments are also described. It is widely believed that quantized circulation is a fundamental property of any superfluid system [1]. The fluid circulation must be quantized in units of h/nm, where m is the mass of the individual atoms in the fluid and n is an integer that depends on the microscopic process responsible for the macroscopic quantum state. For the case of 4He, the interacting atoms experience a Bose condensation into the superfluid state and n = 1. This fact has been demonstrated in several different types of experiments [1].

K.H. Bennemann, John B. Ketterson

Nikolay N. Bogolubov

P.-E. Roche, C. F. Barenghi

We discuss a recent experiment in which the spectrum of the vortex line density fluctuations has been measured in superfluid turbulence. The observed frequency dependence of the spectrum, f − 5/3 , disagrees with classical vorticity spectra if, following the literature, the vortex line density is interpreted as a measure of the vorticity or enstrophy. We argue that the disagrement is solved if the vortex line density field is decomposed into a polarised field (which carries most of the energy) and an isotropic field (which is responsible for the spectrum).

Slenczka, Alkwin, Jan Peter Toennies

This open access book covers recent advances in experiment using ultra-cold, weakly perturbing superfluid environment provided by helium nanodroplet

F.W. Cummings, James R. Johnston