Levitodynamics of optically active nanocrystals

Abstract:

Levitated mesoscopic particles, with their intrinsic low coupling to the environment, are ideally suited as hybrid quantum platforms of mesoscopic size and mass. In vacuum, the only coupling to the environment is the levitation field itself, resulting in a mechanical oscillator with a very high-quality factor. Optically levitated systems in vacuum have recently entered the quantum realm with demonstration of cooling to the motional quantum ground state using passive and active feedback methods. The levitated particles in most of these experiments are optically inert such as SiO2 nanospheres. Here we are interested in studying and developing techniques suitable for the stable levitation of optically active nanoparticles, in particular, rare-earth ion activated nanocrystals. Rare-earth ion doped crystals are one of the few materials enabling laser refrigeration through anti-Stokes fluorescence which is particularly relevant for levitation in vacuum as it enables control over the internal temperature of the levitated nanoparticle. This is particularly relevant since the internal temperature of the particle will limit the coherence of the oscillator. We will present the absolute spectroscopy (of the oscillator and the optically active ensemble) of different nanoparticle designs. In particular we will show refrigeration down to 150k from room temperature of a levitated nanocrystal. We will also show control of the temperature of the oscillator paving the way to the absolute cooling of a levitated nanoparticle. Our approach would enable access to advanced tools for the quantum manipulation of levitated mesoscopic systems, opening up new avenues for accessing fundamental physics.

Bio:

Dr Cyril Laplane graduated from the University of Lyon - France in 2012 with a Master in Nanoscale Engineering. He then moved to Geneva to do a PhD in the Group of Applied Physics under the supervision of Prof. Nicolas Gisin. There he developed and studied solid-state quantum memories for light with application in quantum communication. He defended his thesis in 2016 and in 2017 moved to Sydney to work on the optomechanical manipulation of nanodiamonds at Macquarie University. Mid-2020 Dr Laplane was awarded a Sydney Quantum Academy Postdoctoral fellowship to develop quantum sensors based on levitated nanocrystals and since then has been making all kind of small crystals fly.