Efficient collisional blockade loading of a single atom into a tight microtrap

We show that controlled inelastic collisions can improve the single atom loading efficiency in the collisional blockade regime of optical microtraps. A collisional loss process where only one of the colliding atoms is lost, implemented during loading, enables us to kick out one of the atoms as soon as a second atom enters the optical microtrap. When this happens faster than the pair loss, which has limited the loading efficiency of previous experiments to about 50%, we experimentally observe an enhancement to 80%. A simple analytical theory predicts the loading dynamics. Our results open up an efficient and fast route for loading individual atoms into optical tweezers and arrays of microtraps that are too tight for easy implementation of the method reported in [1, 2]. The loading of tight traps with single atoms is a requirement for their applications in future experiments in quantum information processing and few-body physics.