Microwave-induced orbital angular momentum transfer

Microwave imaging of spinning object using orbital angular momentum

Optical orbital angular momentum.

We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next...

Acoustic rotational manipulation using orbital angular momentum transfer.

We report on the first quantitative test of acoustic orbital angular momentum transfer to a sound absorbing object immersed in a viscous liquid. This is done by realizing an original experiment that is to spin a millimeter-size target disk using an ultrasonic vortex beam. We demonstrate the balance between the acoustic radiation torque calculated from the Brillouin stress tensor and the viscous...

Transfer of optical orbital angular momentum to a bound electron

Photons can carry angular momentum, not only due to their spin, but also due to their spatial structure. This extra twist has been used, for example, to drive circular motion of microscopic particles in optical tweezers as well as to create vortices in quantum gases. Here we excite an atomic transition with a vortex laser beam and demonstrate the transfer of optical orbital angular momentum to ...

Photon Orbital Angular Momentum in Astrophysics

Astronomical observations of the orbital angular momentum of photons, a property of electromagnetic radiation that has come to the fore in recent years, have apparently never been attempted. Here, I show how measurements of this property of photons have a number of astrophysical applications. Subject headings: Instrumentation: Miscellaneous – Masers – ISM: General – Extraterrestrial Intelligenc...