Josephson effect and phase slippage in superfluids

Abstract

By operating a miniature two-hole Helmholtz oscillator equippedwith a submicron aperture in 4He and3He superfluid baths, we have been able to observe individual phase slips events as well as characteristic staircase patterns similar to those observed in electrodynamic rf-SQUIDs.The residual vorticity trapped in the loop formed by the two holes can be studied and has been found not to change in time unless strong perturbations are applied. This device is capable of detecting minute absolute rotations. In 3He-B, the current-phase relation in the weak link is observed to become nearly sinusoidal close to the superfluid transition temperature, corresponding to a near-ideal superfluid Josephson effect. © The Japan Society of Applied Physics.