Matter-wave Interference and Precision Tests of Gravity with Levitated Nano-spheres

Optical levitation in ultra-high vacuum (UHV) and cryogenic environments provides a platform potentially capable of providing quantum coherences of tens to hundreds of milliseconds for objects such as silica nano-spheres which are much more massive than atoms and molecules. Demonstration of matter-wave interference with optically levitated nanospheres has the potential to extend the current limit on matter-wave interference by three to four orders of magnitude, pushing the experimental limits on matter-wave duality. This would provide pathways towards the realization of gravity-induced entanglement experiments, tests of decoherence and wave function collapse models. To preserve a coherence time of approximately 200ms, experimental challenges such as near motional ground state cooling pressures below 10⁻¹³mbar, internal temperatures below 100K, and relative position stability on the order of tens of nanometers must be overcome. This apparatus additionally allows for precision measurements of short-range forces to test Newtonian gravity at sub-micron scales, the Casimir Polder force, matter neutrality, and other fundamental forces.