Weakly interacting Bose gas in the one-dimensional limit

Abstract

We prepare a chemically and thermally one-dimensional (1D) quantum degenerate Bose gas in a single microtrap. We introduce a new interferometric method to distinguish the quasicondensate fraction of the gas from the thermal cloud at finite temperature. We reach temperatures down to kT≈0. 5ω(transverse oscillator eigenfrequency ω) when collisional thermalization slows down as expected in 1D. At the lowest temperatures the transverse-momentum distribution exhibits a residual dependence on the line density n1D, characteristic for 1D systems. For very low densities the approach to the transverse single-particle ground state is linear in n 1D. © 2010 The American Physical Society.