Properties of a few-body trapped two-component Fermi gas at unitarity*

We consider a trapped two-component Fermi system with even and odd number of fermions N. Unlike fermions interact with a short-range two-body potential which does not support a bound state and is characterized by an infinite scattering length. Using two different numerical techniques, i.e., a correlated Gaussians basis expansion method and a fixed-node diffusion Monte Carlo method, we solve the many-body Schrodinger equation and determine the spectrum and structural properties. Analyzing the excitation spectrum and the wavefunctions, we demonstrate that this system exhibits unique universal properties [1], in agreement with analytical predictions [2]. Furthermore, we determine the excitation gap up to N = 30 and we compare it with recent predictions. [1] D. Blume, J. von Stecher, and Chris H. Greene, e-print arXiv:cond-mat/0708.2734 [2] F. Werner and Y. Castin, Phys. Rev. A 74, 053604 (2006).