Cold-atom gas at very high densities in an optical surface microtrap

Abstract

An optical microtrap is realized on a dielectric surface by crossing a tightly focused laser beam with an horizontal evanescent-wave atom mirror. The nondissipative trap is loaded with ∼10 5 cesium atoms through elastic collisions from a cold reservoir provided by a large-volume optical surface trap. With an observed 300-fold local increase of the atomic number density approaching 10 14 cm −3 , unprecedented conditions of cold atoms close to a surface are realized.

Thermodynamics of a multicomponent-atom sample in a tightly compressed atom trap

“…The results agree well with the experiments of Ref. [12], where the phase space density was locally increased by two orders of magnitude using a "dimple" trap within a GOST. It can be seen that at each fixed value of , there is an optimum value of ͉⌬ f ͉ / T 0 , at which the phase-space density reaches its maximum.…”

“…These conditions can be satisfied, e.g., in evanescent-wave cooling of atoms in a GOST [12,[15][16][17][18]. In fact, a "dimple" subtrap created in a GOST with an infrared focused laser beam is frequently employed [12,15]. Figure 2(a) shows the final temperature, T f ͑⌬ i , ͒, that can be achieved by using a subtrap of initial depth ͉⌬ i ͉ ͑⌬ i Ͻ 0͒ and effective volume characterized by .…”

“…This method can be applied if the cooling efficiency does not change in the presence of the subtrap and if the cooled sample can reach thermal equilibrium before the cooling mechanisms are switched off. These conditions can be satisfied, e.g., in evanescent-wave cooling of atoms in a GOST [12,[15][16][17][18]. In fact, a "dimple" subtrap created in a GOST with an infrared focused laser beam is frequently employed [12,15].…”

“…It cannot be increased by scaling the trapping potential [9,10], but may be substantially adjusted by adiabatically deforming the trap [10][11][12][13]. This is also the case in evaporative cooling, where the trap is deformed in order to release atoms with a high kinetic energy.…”

Evaporative cooling of cold atoms at surfaces

“…Since the advent of microchip traps for cold atoms [1][2][3][4][5][6][7][8][9][10][11][12], interest in developing quantum hybrid systems, which exploit the long coherence times of Bose-Einstein condensates with the flexibility of modern micro-and nanoelectronics, continues to grow. There is potential to use such systems as quantum memory devices [13][14][15], precision measurement devices [16][17][18][19] and even rewritable electronic systems [20].…”