nm) optical tweezer, which leads to relatively minor differential (ground vs. excited state) Stark shifts. We demonstrate that simple and robust loading, cooling, and imaging can be achieved through a combined addressing of the D

_\textrm{1}

and D

_\textrm{2}

transitions. While imaging on the D

_\textrm{2}

transition, we can simultaneously apply

Λ

-enhanced gray molasses (GM) on the D

_\textrm{1}

transition, preserving low backgrounds for single-atom imaging through spectral filtering. Using D

_\textrm{1}

cooling during and after trap loading, we demonstrate enhanced loading efficiencies as well as cooling to low temperatures. These results suggest a simple and robust path for loading and cooling large arrays of potassium atoms in optical tweezers through the use of resource-efficient near-detuned optical tweezers and GM cooling.

DOI: 10.48550/arxiv.2108.11895

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Gray molasses cooling of

^{39}

K atoms in optical tweezers

^{39}

K atoms trapped in a near-detuned (

780

_\textrm{1}

and D

_\textrm{2}

transitions. While imaging on the D

_\textrm{2}

transition, we can simultaneously apply

Λ

-enhanced gray molasses (GM) on the D

_\textrm{1}

transition, preserving low backgrounds for single-atom imaging through spectral filtering. Using D

_\textrm{1}

Λ

-enhanced gray-molasses loading and EIT cooling of neutral atoms in nanophotonic traps

Λ

-enhanced gray-molasses (

Λ

GM) can substantially increase the number of trapped atoms in a nanofiber-based cold-atom setup. Specifically, we observe a six-fold increase in the number of loaded atoms compared to conventional red-detuned polarization gradient cooling. Despite the unusually small depth of our optical trap of only 24

μ

K, we load about 4000 individual Cesium atoms, achieving optical depths exceeding 140 and reaching the collisional blockade regime over a length of approximately 1 mm. After loading, we perform efficient EIT-assisted cooling that is found to increase the trap storage time to 400(9) ms. This is a 5-fold improvement over the passive storage time. Remarkably, EIT-cooling also works with two co-propagating nanofiber-guided light fields and requiries only about a few hundred picowatt of optical power. Our results provide an efficient method to boost both the number of loaded atoms and the storage time of nanophotonic atom traps.