Detection of Small Spinor Condensates in Optical Traps

Mickie Eikenberry, Tao Tang, Zihe Chen +2 more

R. Gartman, Marcin Piotrowski, J. Szczepkowski +3 more

Most of spinor condensates studied so far were produced in situ in dipole optical traps. Our new method allows production of spinor condensates in an expanding atomic cloud. Since the spinor condensate is created outside the trap, the Bose –E instein condensate can be prepared in any trap, either magnetic or optical dipole, which significantly extends the experimental flexibility. The described method permits also study of collisions between low density spinor condensates.

Chih-Yuan Huang, Chun-Chia Chen, Li-An Sun +4 more

Abstract We present a simple recipe for the rapid formation of spinor Bose–Einstein condensates of 87 Rb atoms in a three-beam crossed optical dipole trap (ODT). Two laser Gaussian beams were crossed at a small angle to form an effective single potential in the intersection region with an independent and widely tunable trap volume and aspect ratio, for both efficient atom loading and number density enhancement. A third Gaussian beam was then introduced to create a potential dimple at the trap center to further increase the atom number density and collision rate, which enabled rapid evaporation to a Bose condensation. In this configuration, 2 × 10 6 atoms were loaded into the three-beam crossed trap from a vapor cell magneto-optical trap, and condensates of 3 × 10 4 – 4.5 × 10 4 atoms were created after 3–5 s of rapid evaporation. The demonstration of efficient and robust BEC production in this ODT suggests the applicability of this trapping geometry to lasers with any far off-resonant wavelengths. To prepare the spinor condensates with a wide tunability of spin population, control of the magnetic fields was first employed during evaporation to polarize the spin states, and the tuning mechanism is discussed. Spinor condensates with an arbitrary spin population were then created via multiple microwave pulses driving the ground hyperfine transitions.

Dan Stamper-Kurn, Wolfgang Ketterle

Pang Wei, Zhibing Li, Bao Cheng-guang

The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the chemical potentials. These equations are solved numerically for 23 Na and 87 Rb condensates. The deformed trap shows significant effects on the spectrum. This implies that the spin effect of the spinor BEC are more easily detected in an optical trap of larger aspect ratio.