Shot Noise Acoustic Radiation Generated by Phase Slippage in Superfluid4He

Abstract

We present a model calculation and measurements of the acoustic radiation spectrum generated by thermally activated phase slippage driven by a constant pressure head. The calculation of the spectrum, which is similar to that for shot noise in an electrical current, takes into account the stochastic nature of phase-slip vortex nucleation. The observed acoustic amplitude depends on the driving pressure $\ensuremath{\Delta}P$, the frequency $\ensuremath{\omega}$, and the quality factor $Q$ of a coupled cavity, as $(\ensuremath{\Delta}PQ/{\ensuremath{\omega}}^{5}{)}^{1/2}$, consistent with the model predictions.