Observation of the Larmor and Gouy rotations with electron vortex beams.

Imaging the dynamics of free-electron Landau states

Landau levels and states of electrons in a magnetic field are fundamental quantum entities underlying the quantum Hall and related effects in condensed matter physics. However, the real-space properties and observation of Landau wave functions remain elusive. Here we report the real-space observation of Landau states and the internal rotational dynamics of free electrons. States with different ...

Electron Singularities, Matter Wave Catastrophes, and Vortex Lattice Singularimetry

Singularities in wave fields, such as phase vortices, are of substantial interest for light optics, matter waves and x-ray optics. New theoretical insights [1] and cutting edge nanofabrication techniques have recently created a wide variety of electron vortex beams [2, 3] for the transmission electron microscope (TEM), which can provide spectroscopic information pertaining to the magnetic prope...

Direct observation of Gouy phase shift in a propagating optical vortex.

Direct observation of Gouy phase shift on an optical vortex was presented through investigating the intensity profiles of a modified LG_p;m beam with an asymmetric defect, around at the focal point. It was quantitatively found that the rotation profile of a modified LG_p;m beam manifests the Gouy phase effect where the rotation direction depends on only the sign of topological charge m. This pr...

Observation of gold nanoparticles movements under sub-10 nm vortex electron beams in an aberration corrected TEM

Light beams with fractional orbital angular momentum and their vortex structure.

Light emerging from a spiral phase plate with a non-integer phase step has a complicated vortex structure and is unstable on propagation. We generate light carrying fractional orbital angular momentum (OAM) not with a phase step but by a synthesis of Laguerre-Gaussian modes. By limiting the number of different Gouy phases in the superposition we produce a light beam which is well characterised ...