The Nanoparticles’ Quantum Optical Chilling

As a particle is secluded from its environment, the quantum physics laws begin playing a vital part. A significant condition to observe quantum effects is to eliminate the thermal energy from the motion of the particle, to chill it closest to zero temperature. Researchers at the University of Vienna, the Austrian Academy of Sciences and MIT have started demonstrating a new technique for the cooling of these levitated nanoparticles.

Closely fixated laser beams trap and handle tiny matters, ranging from glass particles to alive cells. Most experiments performed up until now are carried out in air/liquid, however, there is a rising interest in utilizing these optical tweezers to trap matters in ultra-high vacuum: such secluded particles display unparalleled sensing ability and can also be utilized in studying central processes involved in nanoscopic heat engines, etc.

A chief factor in these studies is to acquire complete control over the particle motion, preferably in a system where the quantum physics laws govern its conduct. Earlier attempts to attain this have resulted in modulating the optical tweezer or submerging the matter into additional light fields between optical cavities. “Our new cooling scheme is directly borrowed from the atomic physics community, where similar challenges for quantum control exist”, stated Uros Delic, the lead author of the study by researchers at the University of Vienna, the Austrian Academy of Sciences and MIT. The idea follows the studies that established that it is adequate to use the light that is dispersed directly from the optical tweezer, the provided matter is kept inside a vacant optical cavity.

A nanoparticle inside an optical tweezer disperses a small segment of the tweezer light in almost all sides. If the matter is placed inside an optical cavity a segment of the dispersed light can be kept between its mirrors. Consequently, photons are favorably dispersed into the optical cavity. But this is only likely for the light of particular photon energies. If we utilized tweezer light such that it corresponded to faintly lesser photon energy than needed, the nanoparticles will give a little of their kinetic energy to permit photon scattering. This loss in kinetic energy successfully cools the motion.

“Our cooling method is much more powerful than all the previously demonstrated schemes. Without the constraints imposed by laser noise and laser power quantum behavior of levitated nanoparticles should be around the corner”, Delic stated