Search

The phenomenon of superfluidity, which so far has only been observed for [sup.4]He below the transition temperature [T.sub.[Lambda]] = 2.12 K and for [sup.3]He below [T.sub.[Lambda]] = 3 x [10.sup.-3] […]

Photographs are presented of isolated superfluid helium-4 droplets prepared on a cesium surface, the only material known that is not wetted by superfluid helium. Although thermodynamic measurements show that the cesium surface is highly uniform, the contact angle of the droplets is extremely hysteretic and depends on whether the contact line is advancing or receding. Superfluid helium-4 droplets on an inclined surface do not flow downhill but rather are strongly pinned to the surface., Superfluid He has unusual thermal and mechanical properties (1) and is well known for its ability to spread over surfaces and to flow without dissipation through even microscopic holes. Virtually [...]

A quasi-two-dimensional set of electrons (1 [is less than] N [is less than] [10.sup.9]) in vacuum, trapped in one-dimensional hydrogenic levels above a micrometer-thick film of liquid helium, is proposed as an easily manipulated strongly interacting set of quantum bits. Individual electrons are laterally confined by micrometer-sized metal pads below the helium. Information is stored in the lowest hydrogenic levels. With electric fields, at temperatures of [10.sup.-2] kelvin, changes in the wave function can be made in nanoseconds. Wave function coherence times are 0.1 millisecond. The wave function is read out with an inverted dc voltage, which releases excited electrons from the surface., There is much interest in constructing analog quantum computers (AQC). Such objects would solve problems that could never be solved by any classical digital computer, even ones that were hundreds [...]

It is shown that in the low-temperature (0.37 kelvin) environment of superfluid helium droplets, long-range dipole-dipole forces acting between two polar molecules can result in the serf-assembly of noncovalently bonded linear chains. At this temperature the effective range of these forces is on the nanometer scale, making them important in the growth of nanoscale structures. In particular, the self-assembly of exclusively linear hydrogen cyanide chains is observed, even when the folded structures are energetically favored. This suggests a design strategy for the growth of new nanoscale oligomers composed of monomers with defined dipole (or higher order) moment directions., It is well known that as two point dipoles approach from long range they prefer to orient in a head-to-tail configuration (1). An analogous and perhaps more familiar case is [...]