Recent experimental and theoretical work has shown that there are conditions in which a trapped, low-density Bose gas behaves like the one-dimensional delta-function Bose gas solved years ago by Lieb and Liniger. This is an intrinsically quantum-mechanical phenomenon because it is not necessary to have a trap width that is the size of an atom -- as might have been supposed -- but it suffices merely to have a trap width such that the energy gap for motion in the transverse direction is large compared to the energy associated with the motion along the trap. Up to now the theoretical arguments have been based on variational - perturbative ideas or numerical investigations. In contrast, this paper gives a rigorous proof of the one-dimensional behavior as far as the ground state energy and particle density are concerned. There are four parameters involved: the particle number, $N$, transverse and longitudinal dimensions of the trap, $r$ and $L$, and the scattering length $a$ of the interaction potential. Our main result is that if $r/L\to 0$ and $N\to\infty$ the ground state energy and density can be obtained by minimizing a one-dimensional density functional involving the Lieb-Liniger energy density with coupling constant $\sim a/r^2$.
Lee-Huang-Yang Energy for Dilute Bose Gases: an Upper Bound for General Potentials
Department of Mathematics “Guido Castelnuovo”, La Sapienza（罗马第一大学数学系）；Institute of Mathematics, University of Zurich（苏黎世大学数学研究所）；Gran Sasso Science Institute（格兰萨索科学研究所）；Dipartimento di Matematica, Politecnico di Milano（米兰理工大学数学系）
