Dr. Roya Zandi
UCLA Department of Physics & Astronomy

Casimir forces, surface fluctuations, and thinning of superfluid films

Experiments on the wetting of helium by Garcia and Chan have shown that the film thickness is reduced at the normal to superfluid transition, and remains thinner in the superfluid phase. The difference in thickness above and below the transition has been attributed to a Casimir interaction which is a consequence of a broken continuous symmetry in the bulk superfluid. However, the observed thinning of the film is larger than can be accounted by this Casimir force. We show that surface fluctuations give rise to an additional force, similar in form but larger in magnitude, which can explain the observations