By Andrew G. Truscott, Kevin E. Strecker, William I. McAlexander, Guthrie B. Partridge, Randall G. Hulet. Science 291(5513), 2570–2572, 30 March 2001. IIT Delhi hosts this journal reprint. The 14 April 2008 cover timestamp records a download, not publication.
Cited passages: pp. 2570–2572, Figures 1–3.
Sequential absorption imaging recorded both trapped clouds on a camera. Fits to axial profiles used the boson cloud as a thermometer. At common temperature, the nearly equal magnetic trapping potentials provided a comparison: the clouds had similar sizes near , but the fermion cloud remained broader as cooling reached . Figure 3 compared its radius with ideal Fermi gas and classical predictions.[ref]
Varying the wait before imaging tested thermal equilibrium. Finite imaging resolution restricted the analysis to the axial direction; fits neglected interaction-induced density shifts. Cooling eventually suffered from the dwindling boson heat capacity. The result supports quantum occupation effects, without directly resolving individual occupied states or reaching zero temperature.[ref]
These were neutral alkali atoms in a spatially varying trap. The Fermi energy of a model electron gas instead uses uniform Electrons, two equally populated spin states, and the Electron mass. The measured trapped-atom radii are not measurements of that electron model's or ; comparing their numerical Fermi energies requires the appropriate particle mass, internal-state populations, and confining potential.