Observation of Fermi Pressure in a Gas of Trapped Atoms

We report the attainment of simultaneous quantum degeneracy in a mixed gas of bosons (lithium-7) and fermions (lithium-6). The Fermi gas has been cooled to a temperature of 0.25 times the Fermi temperature by thermal collisions with the evaporatively cooled bosons. At this temperature, the spatial size of the gas is strongly affected by the Fermi pressure resulting from the Pauli exclusion principle and gives clear experimental evidence for quantum degeneracy.

[1]  On the possibility of a superfluid transition in a Fermi gas of neutral particles at ultralow temperatures , 1996 .

[2]  Klaus Mølmer,et al.  Bose Condensates and Fermi Gases at Zero Temperature , 1998 .

[3]  Andrews,et al.  Bose-Einstein Condensation in a Tightly Confining dc Magnetic Trap. , 1996, Physical review letters.

[4]  C. Sackett,et al.  Bose–Einstein condensation of lithium , 1997 .

[5]  Hulet,et al.  Superfluidity of spin-polarized 6Li. , 1995, Physical review letters.

[6]  D. Kleppner,et al.  Bose-Einstein condensation in an external potential. , 1987, Physical review. A, General physics.

[7]  K. B. Davis,et al.  Bose-Einstein Condensation in a Gas of Sodium Atoms , 1995, EQEC'96. 1996 European Quantum Electronic Conference.

[8]  A. Leggett,et al.  Some properties of a spin-1 fermi superfluid: Application to spin-polarized6Li , 1997 .

[9]  Bradley,et al.  Evidence of Bose-Einstein Condensation in an Atomic Gas with Attractive Interactions. , 1995, Physical review letters.

[10]  D. Jin,et al.  Onset of fermi degeneracy in a trapped atomic Gas , 1999, Science.

[11]  Wineland,et al.  Sympathetic cooling of trapped ions: A laser-cooled two-species nonneutral ion plasma. , 1986, Physical review letters.

[12]  J. Ketterson,et al.  The Physics of Liquid and Solid Helium , 1976 .

[13]  B. Verhaar,et al.  Sympathetic cooling of {sup 6}Li atoms , 1997 .

[14]  C. Wieman,et al.  Observation of Bose-Einstein Condensation in a Dilute Atomic Vapor , 1995, Science.

[15]  Verhaar,et al.  Threshold and resonance phenomena in ultracold ground-state collisions. , 1993, Physical review. A, Atomic, molecular, and optical physics.

[16]  Carl E. Wieman,et al.  PRODUCTION OF TWO OVERLAPPING BOSE-EINSTEIN CONDENSATES BY SYMPATHETIC COOLING , 1997 .