Non-equilibrium optically levitated interacting nanoparticle arrays

We propose the exploration of many-body quantum physics with a new experimental platform, based on the

optically levitated and cooled arrays of spherical nanoparticles with strong and controllable interactions. The

recent works by the host institution demonstrated the cavity assisted cooling of a single nanoparticle to its

motional quantum ground state as well as the simultaneous trapping of two nanoparticles with full control

over the interactions between them. In this work we shall extend these results to the multiple particles. This

will be on the one hand an important milestone towards achieving the many-body regime and on the other

hand, the first observation of the cavity assisted cooling of an array of nanoparticles via coherent light

scattering. The realisation of this milestone will enable us to study the system’s non-equilibrium relaxation after

precise perturbation protocols. Using the natural isolation from the environment, we shall study the

thermalisation of a nearly isolated few-particle quantum system. Depending on the energetic landscape, as well

as on the nature and range of interactions, we expect to observe motional pre-thermalisation, or the absence

of thermalisation with the onset of the Anderson localisation or the Many-Body Localisation of phonons. Finally,

we shall explore the controllable non-reciprocity of the inter-particle interactions by breaking the directional

symmetry of the inter-particle forces by conferring to them the direction dependent phases. Combining this

with the dissipative nature of these forces, we aim at implementing a specifically tailored non-hermitian

Hamiltonian describing the constant intensity waves.