Liquid Helium

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

Akihiro Fujisaki, K. Sano, Toshiya Kinoshita +2 more

We have developed a new method for producing a high density of neutral atoms in liquid helium; laser sputtering within liquid helium. When we irradiate samples immersed in liquid helium with a pulsed laser, a large number of clusters are introduced into the liquid. When we further irradiate these clusters with an additional pulse laser, the clusters are sputtered and decomposed, which results in the creation of a high density of isolated atoms in the liquid. For alkaline earth atoms this method is demonstrated, and the results of laser spectroscopy are given.

David M. Ceperley, E. L. Pollock

Path-integral methods can be employed to calculate properties of boson systems at any temperature. We have performed a number of simulations of liquid helium and have calculated the momentum distribution as a function of temperature. We find that liquid helium has a condensate below 2 K but not above. The momentum distribution is found to be non-Gaussian even in normal liquid helium. We have also calculated the difference in the momentum distribution between a boson system and a distinguishable particle system.

T Yamazaki

D. G. Rees, P. Glasson, Vladimir N Antonov +7 more

Surface‐state electrons on liquid helium, have been proposed as condensed matter qubits. We have demonstrated that small numbers of electrons, including a single isolated electron, can be held in an electrostatic trap above the surface of superfluid helium and individually detected using a superconducting single‐electron transistor (SET). A new design for a quantum information processor, using an array of electron traps on liquid helium, has been fabricated on a Si wafer using a superconducting A1 SET.