A Simplified Projected Optical Trap Array

Arrays of optical traps are ubiquitous in cold atom experiments, including quantum computing and quantum simulation, due to their stability and versatility. However, the optical trains for creating these traps are often complicated, space-consuming, and expensive, requiring active electro-optical devices. Here we present an approach for trapping cold atoms in a 2D optical trap array generated with a novel 4f filtering scheme and custom transmission mask without any active device. The approach can be used to generate arrays of bright or dark traps, or both simultaneously in customizable configurations. Using blue-detuned light, single atoms are loaded into regions of near-zero intensity in an approximately Gaussian profile trap. Moreover, we demonstrate a simple solution to the problem of out-of-focus trapped atoms, which occurs due to the Talbot effect in periodic optical lattices. In such cases, atoms trapped out-of-focus lead to higher background in fluorescence measurements, complicating single atom imaging and control. By using a relatively inexpensive spectrally and spatially broadband laser, out-of-focus interference is mitigated, leading to near perfect removal of Talbot plane traps.