Transition from phase slips to the Josephson effect in a superfluid 4He weak link

Abstract

The rich dynamics of flow between two weakly coupled macroscopic quantum reservoirs has led to a range of important technologies. Practical development has so far been limited to superconducting systems, for which the basic building block is the so-called superconducting Josephson weak link1. With the observation of quantum oscillations2 in superfluid 4He near 2 K, we can now envision analogous practical superfluid helium devices. The characteristic function that determines the dynamics of such systems is the current–phase relation Is(ϕ), which gives the relationship between the superfluid current Is flowing through a weak link and the quantum phase difference ϕ across it. Here we report the measurement of the current–phase relation of a superfluid 4He weak link formed by an array of nano-apertures separating two reservoirs of superfluid 4He. As we vary the coupling strength between the two reservoirs, we observe a transition from a strongly coupled regime in which Is(ϕ) is linear and flow is limited by 2π phase slips, to a weak-coupling regime where Is(ϕ) becomes the sinusoidal signature of a Josephson weak link.

Cite this article

Hoskinson, E., Sato, Y., Hahn, I. et al. Transition from phase slips to the Josephson effect in a superfluid ⁴He weak link. Nature Phys 2, 23–26 (2006). https://doi.org/10.1038/nphys190

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