We smoothly tune the dimensionality of pancake-shaped ${}^6\mathrm{Li}$ Fermi gas clouds from quasi-two-dimensional to two-dimensional (2D) to measure radio-frequency spectra and cloud profiles in both regimes. In the quasi-2D case, where $E_F/h{\nu }_z\simeq 1$, with $E_F$ the Fermi energy and $h{\nu }_z$ the harmonic oscillator energy in the tightly confined direction, we confirm that the radio-frequency spectra strongly disagree with 2D mean-field theory. Then we tune to the 2D regime, $E_F<<h{\nu }_z$, where the measured radio-frequency spectra are in very good agreement with 2D mean-field theory. Nevertheless, the measured cloud profiles strongly disagree, confirming predictions that a beyond mean-field approach is required throughout the 2D to quasi-2D crossover.

• Received 20 April 2016
• Revised 16 June 2016

DOI:https://doi.org/10.1103/PhysRevA.94.031606