Sawtooth wave adiabatic passage in a grating magneto-optical trap

Abstract

We demonstrate sawtooth wave adiabatic passage (SWAP) in a grating magneto-optical trap (MOT) operating on the ${}^1$S${}_0$ $\to$ ${}^3$P${}_1$ transition of neutral ${}^{88}$Sr. From numerical simulations of SWAP using our laser beam geometry, we find that SWAP provides greater cooling than triangle wave frequency modulation despite the complex polarization environment of a grating MOT. The simulation is confirmed by our experimental results, where we demonstrate a factor of two improvement in transfer efficiency between our ${}^1$S${}_0$ $\to$ ${}^1$P${}_1$ grating MOT and our ${}^1$S${}_0$ $\to$ ${}^3$P${}_1$ grating MOT. We trap up to $3\times 10^6$ ${}^{88}$Sr atoms in the ${}^1$S${}_0$ $\to$ ${}^3$P${}_1$ grating MOT, at an average temperature of 4.9 $\mu$K with a lifetime of approximately 0.7 s. Our results show that SWAP is effective in non-orthogonal laser beam geometries, allowing greater duty cycles or higher atom number in sensors based on narrow-line grating MOTs.

9 pages, 7 figures