High-power optical transport of ultracold fermions using focus-tunable lens*

We present an all-optical setup designed to transport a trapped cold cloud of $^6$Li over a macroscopic distance of 30 cm, based on a focus-tunable lens. We transport the atoms from the initial preparation chamber to a dedicated glass cell with increased optical access by displacing the focus of the focus-tunable lens. We estimate the transport efficiency by measuring the atom number and temperature both before and after the transfer. We further characterize the loading and post-transport focus stability. We show that the atom number and focus fluctuation amplitudes can be greatly reduced by an stabilization of lens temperature and the focus-tunable lens control current. We demonstrate the robustness of the optical transport by preparing a molecular BEC after transporting the atoms to the glass cell.