Levitated nanoparticle detects single

A silica nanoparticle levitated in an optical trap could be used as a tiny pressure sensor that detects collisions with individual atoms and molecules – according to researchers in the US. Their proof-of-principle demonstration originated in the team’s work in developing novel neutrino and dark-matter detectors. It could lead to the development of a background pressure sensor to work alongside other optomechanical sensors.

In recent years, physicists have proposed that hypothetical particles such as dark matter could be detected when they occasionally scatter from nanometre-sized objects held in optical traps. Alternatively, if a nano-object contains a radioactive substance, the kinetics of the decay products could be studied by observing the object’s recoil. To make such detections however, physicists must understand the nature of background collisions between nanoparticles and residual gases in their vacuum chamber.