How to achieve supersolidity We are presently interested in the solid (hcp) phase of helium, and more specifically we are trying to realize the so-called Andreev, Lifshitz, Chester (ALC) scenario to the supersolidity. Supersolidity is a state in which, although remaining crystalline, part of the solid would behave as a superfluid, thanks to a finite population of vacancies at low temperature.
Spectroscopy of implanted cesium atoms Since a couple decades one knows how to dope liquid or solid helium with foreign, metallic atoms. The case of solid is particularly appealing, and let imagine fundamental measurements.
The cristalline matrix perturbs implanted atoms : in the case of the hcp phase, this perturbation is anisotropic. We have studied the spectroscopic properties of cesium atoms implanted in single crystals of helium, revealing the shape of the indvidual bubble in wich they stay. This has been the PhD work of Mathieu Melich, defended in september 2008.