Superfluidity and excitations at unitarity
Abstract
We present lattice results for spin-1/2 fermions at unitarity, where the effective range of the interaction is zero and the scattering length is infinite. We measure the spatial coherence of difermion pairs for a system of 6, 10, 14, 18, 22, 26 particles with equal numbers of up and down spins in a periodic cube. Using Euclidean time projection, we analyze ground state properties and transient behavior due to low-energy excitations. At asymptotically large values of t we see long-range order consistent with spontaneously broken U(1) fermion-number symmetry and a superfluid ground state. At intermediate times we see exponential decay in the t-dependent signal due to an unknown low-energy excitation. We probe this low-energy excitation further by calculating two-particle correlation functions. We find that the excitation has the properties of a chain of particles extending across the periodic lattice.
Cite
@article{arxiv.cond-mat/0606706,
title = {Superfluidity and excitations at unitarity},
author = {Dean Lee},
journal= {arXiv preprint arXiv:cond-mat/0606706},
year = {2008}
}
Comments
40 pages, 19 figures, revised version includes new data on two-particle density correlations