Search Results (2 total)

We have discovered new features of the current-phase relation, I(φ), in superfluid ³He weak links. Firstly, we find that at any given temperature there are two distinct I(φ) functions that characterize the weak link. Secondly, both functions continuously develop an unusual form that ultimately leads to the previously reported π state. The observed form of I(φ) has recently been predicted for unconventional quantum fluids such as ³He, high- T_c superconductors, and Bose-Einstein condensates. The two distinct states are likely to originate from the textural degree of freedom in superfluid ³He.

We have discovered that the dc mass current through a superfluid ³He weak link is substantially increased when the Josephson frequency matches the resonant frequency of a coupled mechanical oscillator. The phenomenon is the result of homodyne mixing between the Josephson oscillations and the oscillating pressure field associated with the resonant system. The measured sizes of the current enhancements are in excellent agreement with calculations based on this homodyne model. Similar observations in superconducting junctions, in which microwave radiation changes the dc electronic current, were used for the first confirmation of the dynamics of the superconducting Josephson effect.