Approaching a Supermodel

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Science  17 Feb 2012:
Vol. 335, Issue 6070, pp. 776
DOI: 10.1126/science.335.6070.776-d

Optical lattices, constructed from counter-propagating laser beams and loaded with atoms a fraction of a degree above absolute zero, are slowly fulfilling their potential of simulating solid materials. One of the long-term goals in the field is building a model of a cuprate superconductor, with its layered structure of loosely bound planes. Sommer et al. make a step in that direction by loading a three-dimensional (3D) gas of fermionic atoms of 6Li into a 1D optical lattice; increasing the strength of the optical potential achieves a gradual crossover to a stack of uncoupled 2D layers confined to the successive troughs of the optical lattice. The authors track the formation of the bound pairs of fermions, crucial for the phenomena of superfluidity and superconductivity, by performing rf spectroscopy. As the dimensionality of the system changes, so do its properties; in line with theoretical predictions, the binding energy in the 2D system is independent of the interaction strength and equal to the binding energy in free space. Observation of superfluidity in the 2D layers is probably next on the agenda of simulating a cuprate.

Phys. Rev. Lett. 108, 45302 (2012).

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