Optical levitation is a subfield of optomechanics, in which a nanoparticle is trapped in a vacuum at the focal spot of a microscope objective. Because levitated systems outperform other mechanical resonators, they offer the tantalizing prospect of investigating quantum mechanics at the mesoscale. To display quantum properties, the nanoparticle must be cooled down close to its ground state, which is typically achieved through the monitoring of its displacements and a modulation of the laser’s intensity. Currently, the most exciting endeavor in the field lays in performing levitation with many-body systems. Many-body levitation would offer the opportunity to observe effects for the first time, like the mesoscopic entanglement of nanoparticles. Sadly, conventional cooling techniques, cannot be multiplexed and fail badly to cool several elements in parallel. Throughout this internship, the candidate will experimentally implement a new cooling technique intended to achieve the first-ever cooling of a many-body system composed of multiple nanoparticles in levitation. Compared to former strategies, here, a spatial light modulator is used to spatially shape the wavefront of the laser beam. Such a modulation enables to exert simultaneously adapted optical forces on all the nanoparticles in order to reduce their individual vibrational motions, which ultimately leads to the cooling of the many-body system. A funding is available to continue this internship through a PhD.