Superfluidity in a 1D disordered Hubbard boson model: numerical spectroscopic analysis
Kashurnikov V. A. , Podlivaev A. I. , Svistunov B. V.
Superfludity (at Γ=0) and its suppression by disorder are analyzed in a ID Bose system through an exact diagonalization of a Hamiltonian matrix with a calculation of low-lying excited states. In addition to ordinary phonon excitations in the spectrum, there are some so-called supercurrent states. A sharp change in the splitting of the phonon levels is observed near the theoretical point of the superfluidity/Bose-glass phase transition, which corresponds to the value ë = 2/3 of the universal parameter. A sharp increase in the splitting of the supercurrent levels occurs at a ë value of approximately 1/2. This result does not conform to the current understanding of the situation. © 1995 American Institute of Physics.