Modern low-temperature physics began with the liquefaction of helium by Kamerlingh Onnes (1908) and the discovery of superconductivity (Kamerlingh Onnes, 1911) at the University of Leiden in the early part of the 20th century. There were really two surprises that came out of this early work. One was that essentially all of the electrical resistance of metals like mercury, lead, and tin abruptly...

Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the ‘quantum melting’ of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degene...

Equilibrium properties of hydrogen-helium mixtures under thermodynamic conditions found in the interior of giant gas planets are studied by means of density functional theory molecular dynamics simulations. Special emphasis is placed on the molecular-to-atomic transition in the fluid phase of hydrogen in the presence of helium. Helium has a substantial influence on the stability of hydrogen mol...

A new 300kV, FEG, helium-cooled, energy-filtered "G2 Polara" electron cryoTEM was recently installed at Caltech. Using this instrument, we have now extensively tested the potential advantages of liquid helium cooling and the inclusion of two orthogonal tilt-series in the context of electron cryotomography. These results and the application of the technology to several specific biological proble...