Nonequilibrium in Josephson junctions: A possibility for low-energy radiation/particle detection

It has been suggested recently that 4He can be prepared and studied as a quasi-one-dimensional quantum fluid. In this paper we calculate the static and dynamic properties of one-dimensional 4He using variational methods based upon the Jastrow-Feenberg wave function and its extension to dynamic systems with time-dependent, correlated wave functions. We calculate the zero temperature equation of state and show that in one dimension 4He is just barely self-bound with a binding energy of 0.002 K at a density of 0.036 Å-1. We calculate the Feynman excitation spectrum and corrections that contain multiphonon processes and study the density dependence of the roton feature as well as the static response function. In addition we demonstrate the presence of strong anomalous dispersion in the phonon regime. Finally, we introduce a3He impurity and calculate the zero concentration chemical potential as a function of 4He linear density. We also compute the 3He-3He effective interaction in the 4He background and compute the energy of dimerization. © 1999 The American Physical Society.

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