All-optical saddle trap as a platform for mesoscopic quantum experiments

We investigate the quantum dynamics of a levitated nanoparticle in a structured light rotating saddle-like optical potential consisting of a superposition of Gaussian and Laguerre-Gauss modes with detuned frequencies. This rotating saddle trap offers unique opportunities for quantum experiments, such as reduced decoherence due to photon recoil and absorption, the possibility of delocalization of the particle's center-of-mass motion, particle recovery protocols, the generation of motional entanglement and the preservation of squeezing. As an application, we show that this saddle-trap architecture enables force sensing with a single-shot quantum bound in the attoNewton regime.