Laser Tweezers and Orbital Angular Momentum Photons

Abstract

A photon can be considered both a particle and a wave in quantum mechanics. Quantum
optics deals with such quantum mechanical properties of a photon. One such property that has been
of particular interest recently is that of light’s momentum, specifically its linear momentum and orbital
angular momentum (OAM). Light carrying both types of momentum are of particular utility to
the life sciences. Linear momentum (LM) photons have the ability to directly manipulate particles.
For example, photons with these properties can be used to separate one specific particle from a group.
One can then more closely observe its properties. OAM photons have the potential to unravel DNA
strands using the torque of the photons to further observe certain specific physical properties. Light
carrying OAM has also shown promise in the field of information technology as a new means of sending
large amounts of data over long distances securely and extremely quickly. Because photons behave
quantum mechanically, the encryptions are much more difficult to decode, and since the information
is being sent as light it clearly travels at the speed of light. This paper will provide background on the
quantum optics of particle manipulation and the results from experimental studies performed on this
topic. The results show evidence of light with both types of momentum being created and used to
manipulate particles. We generated light with both types of momentum, trapped particles with optical
tweezers, and measured the force on the particles with a high speed video camera, optical tweezers,
and computer programs that we used to track the particles.