Experimental Investigation of the Influence of the Laser Beam Waist on Cold Atom Guiding Efficiency

The primary purpose of this study is to investigate the influence of the vertical guiding laser beam waist on cold atom guiding efficiency. In this study, a double magneto-optical trap (MOT) apparatus is used. With an unbalanced force in the horizontal direction, a cold atomic beam is generated by the first MOT. The cold atoms enter the second chamber and are then re-trapped and cooled by the second MOT. By releasing a second atom cloud, the process of transferring the cold atoms from MOT to the dipole trap, which is formed by a red-detuned converged 1064-nm laser, is experimentally demonstrated. And after releasing for 20 ms, the atom cloud is guided to a distance of approximately 3 mm. As indicated by the results, the guiding efficiency depends strongly on the laser beam waist; the efficiency reaches a maximum when the waist radius (w0) of the laser is in the range of 15 to 25 μm, while the initial atom cloud has a radius of 133 μm. Additionally, the properties of the atoms inside the dipole potential trap, such as the distribution profile and lifetime, are deduced from the fluorescence images.

[1]  Continuous transfer and laser guiding between two cold atom traps , 2006, quant-ph/0609208.

[2]  R. Grimm,et al.  Optical dipole traps for neutral atoms , 1999, physics/9902072.

[3]  R. Spreeuw,et al.  Guiding of cold atoms by a red-detuned laser beam of moderate power , 2002, physics/0201068.

[4]  W. Ertmer,et al.  Atom optics, guided atoms, and atom interferometry , 2005 .

[5]  T. Walker,et al.  A magneto-optical trap loaded from a pyramidal funnel. , 1998, Optics express.

[6]  Chu,et al.  Trapping of neutral sodium atoms with radiation pressure. , 1987, Physical review letters.

[7]  Walker,et al.  Collective behavior of optically trapped neutral atoms. , 1990, Physical review letters.

[8]  K. Bongs,et al.  Efficient guiding of cold atoms through a photonic band gap fiber , 2010, 1010.0101.

[9]  Tan,et al.  Isotopic difference in trap loss collisions of laser cooled rubidium atoms. , 1992, Physical review letters.

[10]  Laurence Pruvost,et al.  Guiding and cooling of cold atoms in a dipole guide , 1999 .

[11]  C. Adams,et al.  An atomic fountain guided by a far-off resonance laser beam , 1999 .

[12]  Zhou Zhaoying,et al.  Characterization of a velocity-tunable 87Rb cold atomic source with a high-speed imaging technology , 2009 .

[13]  Dana Z. Anderson,et al.  Optical-Dipole-Force-Fiber Guiding and Heating of Atoms , 1997 .

[14]  Cornell,et al.  Laser-guided atoms in hollow-core optical fibers. , 1995, Physical review letters.

[15]  Arthur Ashkin,et al.  Trapping of Atoms by Resonance Radiation Pressure , 1978 .

[16]  Cornell,et al.  Low-Velocity Intense Source of Atoms from a Magneto-optical Trap. , 1996, Physical review letters.

[17]  Chu,et al.  Experimental observation of optically trapped atoms. , 1986, Physical review letters.

[18]  G. S. Summy,et al.  Prospects for atom interferometry , 2001 .

[19]  Phillips,et al.  Observation of atoms laser cooled below the Doppler limit. , 1988, Physical review letters.

[20]  D. Steck.  Rubidium 85 D Line Data , 2008 .

[21]  Cornell,et al.  Reduction of light-assisted collisional loss rate from a low-pressure vapor-cell trap. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[22]  S. Cornish,et al.  Transport of launched cold atoms with a laser guide and pulsed magnetic fields , 2006, physics/0610027.

[23]  J. Mlynek,et al.  Atom Optics , 1998, Technical Digest. 1998 EQEC. European Quantum Electronics Conference (Cat. No.98TH8326).