Physics

Squeezing Fermi Gases into Two Dimensions

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Science  30 Jul 2010:
Vol. 329, Issue 5991, pp. 492-493
DOI: 10.1126/science.329.5991.492-d

Some of the most intriguing many-body effects in solids appear when mobile particles, such as charge carriers, no longer move freely but are confined to reduced spatial dimensions, such as at a planar interface. The importance of fluctuations in the states formed by charge carriers is enhanced with respect to the three-dimensional (3D) case. In these solid-state systems, it can be difficult to tune interaction parameters smoothly, and the presence of defects can lead to scattering effects that complicate the theoretical interpretation of results. One way to simulate the effects of confinement in a tunable and impurity-free environment is to use ultracold Fermi gases. However, although the 3D and 1D trapped gases have been realized, achieving a nearly 2D Fermi gas has been an experimental challenge. Martiyanov et al. place a Fermi gas of lithium atoms into an optical potential that provides loose confinement in the transverse direction, whereas in the axial direction it corresponds to a tight 1D standing wave. This approach results in a 1D chain of pancake-like, 2D trapped Fermi gases. The finite temperature, interaction, and Fermi statistics effects may all cause a portion of the atomic population to leave the axial ground state, which can affect the 2D confinement, but estimates indicate that this portion is very small.

Phys. Rev. Lett. 105, 030404 (2010).

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