Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement

Abstract

We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ∼6nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

Observation of atom-number fluctuations in optical lattices via quantum collapse and revival dynamics

“…Here, F and m F denote the total angular momentum and the magnetic quantum number, respectively, of the atom's hyperfine state. The BEC is prepared in a crossed-beam optical dipole trap with a nearly isotropic trapping frequency 2π × 20 Hz [23]. A cubic optical lattice comprises three mutually orthogonal retroreflected laser beams each with a beam waist of ∼ 145 µm.…”

Superfluid-Mott-Insulator Transition in an Optical Lattice with Adjustable Ensemble-Averaged Filling Factors*

“…The BEC is prepared in a crossed-beam optical dipole trap with a nearly isotropic trapping frequency. [11] A cubic optical lattice comprises three mutually orthogonal retroreflected laser beams each with a beam waist of ∼145 µm. [12] During evaporation cooling, the trapping frequency of the optical dipole trap is enhanced by the gravitational tilting, especially when the effective trap depth is very low, which improves the efficiency of evaporation cooling.…”

One-dimensional atom laser in microgravity*

“…[2] Under microgravity environment in space station, longer investigation time and colder atom clouds can be achieved, which are crucial for precision measurements and quantum physics studies. [1][2][3][4][5][6] The subnanokelvin BEC with one second free expansion time has been realized in microgravity. [1,4] In an Earth-orbiting research laboratory, one group performed manipulation of multi-components BEC experiment in the flight.…”