Sawtooth wave adiabatic passage in a grating magneto-optical trap

TL;DR

This paper demonstrates that sawtooth wave adiabatic passage (SWAP) enhances cooling efficiency and atom transfer in a grating magneto-optical trap for strontium, leading to higher atom numbers and lower temperatures.

Contribution

The study introduces the application of SWAP in a complex polarization environment of a grating MOT, showing improved transfer efficiency and cooling performance over traditional methods.

Findings

SWAP provides greater cooling than triangle wave modulation.

Achieved a twofold increase in transfer efficiency.

Trapped up to 3 million Sr atoms at 4.9 μK.

Abstract

We demonstrate sawtooth wave adiabatic passage (SWAP) in a grating magneto-optical trap (MOT) operating on the $^1$S$_0$ $\rightarrow$ $^3$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$_0$ $\rightarrow$ $^1$P$_1$ grating MOT and our $^1$S$_0$ $\rightarrow$ $^3$P$_1$ grating MOT. We trap up to $3\times10^6$ $^{88}$Sr atoms in the $^1$S$_0$ $\rightarrow$ $^3$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.