Recent progress in the physics of twisted particles

Methods of generation of twisted particle beams

Twisted (vortex) particles with intrinsic orbital angular momenta (OAMs) even in free space are of significant importance in modern physics and have important applications. Twisted photons and electrons were discovered in 1992 and 2010, respectively. The maximum observed OAMs were about 10000 for photons and 1000 for electrons. Recently, twisted neutrons, atoms, and molecules were also discovered. In a magnetic field, charged particles move in a helical trajectory (on a circle in the transverse plane). In the quantum-mechanical picture, a particle trajectory cannot be defined, but its equations of motion are equivalent to the corresponding classical ones. Twisted particles in free space are not under the influence of any external forces. Twisted states appear as the coherent superpositions of noninteracting partial de Broglie waves with different directions of transverse momenta.