Observation of sub-Doppler temperatures in bosonic magnesium

Abstract

Temperatures below the Doppler limit of 1.9 mK have been observed in magnesium. The strong cooling transition was modified by a coherent two-color excitation exploiting the longer lifetime of an upper level. We developed a theoretical model to describe the light forces and cooling originating from the induced quantum interference in a three-level system. Time-of-flight measurements verified temperatures of 500 K in a onedimensional ͑1D͒ molasses in accordance with our theoretical model. By implementing this scheme in a 3D magneto-optical trap with a single ir beam, temperatures as low as 1 mK could be realized. For ideal conditions we extrapolate to temperatures of 50 K. With cooling times of about 1 ms, a fast and efficient cooling scheme was realized, particularly attractive for optical frequency standards.

Absolute frequency measurement of the magnesium intercombination transitionS01→P13

“…A further considerable enhancement in accuracy can only be expected from measurements on laser cooled free falling or in a dipole trap captured atoms in combination with a primary frequency reference with superior stability compared to the presently used Cs clock. Currently we investigate possible experimental strategies [33,34,35,36] to implement a lattice clock, which is expected to improve the current uncertainty in accuracy by several orders of magnitude.…”

Enhanced light-assisted-collision rate via excitation to the long-lived5S1/2-5D5/2Wilson1, Roberts2 2011Phys. Rev. A0000View full textAdd to dashboardCite

“…Light-assisted collisions involving multiple transitions to various excited states could be a limitation in experiments with ultracold gases where excited-state atoms and molecules are created, such as Rydberg atom formation [15][16][17]. It could also impose limitations on extensions of laser cooling involving higher-energy excited states than the first excited state [18][19][20], if the excitation pathway involves similar states. Given the convenience of obtaining diode lasers resonant with the 5P 3/2 -5D 5/2 transition in Rb at 776 nm, the 5D 5/2 state would appear to be an excellent candidate for these studies.…”

Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms – a new hope

“…However, Mg has been successfully laser-cooled [36] whereas Be has not. We therefore focus in this section on developing a complete potential energy surface for interaction of Mg with NH( 3 Σ − ).…”

“…Calcium [34] and strontium [35] atoms can be cooled and trapped at temperatures of the order of µK. Mehlstäubler et al [36] have recently succeeded in cooling magnesium atoms to sub-Doppler temperatures of 500 µK. To our knowledge no attempt has yet been made to cool Be atoms.…”