Generation of electron beams carrying orbital angular momentum

Abstract

All forms of waves can contain phase singularities. In the case of optical waves, a light beam with a phase singularity carries orbital angular momentum, and such beams have found a range of applications in optical manipulation, quantum information and astronomy. Here we report the generation of an electron beam with a phase singularity propagating in free space, which we achieve by passing a plane electron wave through a spiral phase plate constructed naturally from a stack of graphite thin films. The interference pattern between the final beam and a plane electron wave in a transmission electron microscope shows the 'Y'-like defect pattern characteristic of a beam carrying a phase singularity with a topological charge equal to one. This fundamentally new electron degree of freedom could find application in a number of research areas, as is the case for polarized electron beams.

Quantum Čerenkov Radiation: Spectral Cutoffs and the Role of Spin and Orbital Angular Momentum

“…This issue is of great interest today because it recently became possible to shape the quantum wave packet of a single electron [32][33][34][35], imprinting it with OAM [32][33][34][36][37][38] or with other intriguing shapes [35,39].…”

Intricate Physics of Coherent Electron Beam/Oxide Materials Interaction Revealed by 4D Inline Holography—Electron Ptychography

“…This has been an unsurmountable barrier since the initial discovery of an electron vortex beam in 2010. [1,2] To overcome this limitation, Verbeeck and his colleagues offered a solution in their work published in 2010.…”

“…This has been an unsurmountable barrier since the initial discovery of an electron vortex beam in 2010. [1,2] To overcome this limitation, Verbeeck and his colleagues offered a solution in their work published in 2010. [2] Basically as opposed to using the pitch-fork aperture as a way of generating vortex beams above the sample, they used the pitch-fork aperture as a post-specimen chiral analyser.…”

“…This has been an unsurmountable barrier since the initial discovery of an electron vortex beam in 2010. [1,2] To overcome this limitation, Verbeeck and his colleagues offered a solution in their work published in 2010.[2] Basically as opposed to using the pitch-fork aperture as a way of generating vortex beams above the sample, they used the pitch-fork aperture as a post-specimen chiral analyser. Most works that followed Verbeeck et al (2010) only picked up the idea of shaping wave-fronts using a patterned phase plate, but the idea of chiral analyser has largely been overlooked by the field because this part of the results is very difficult to reproduce.…”

Measuring Orbital Angular Momentum (OAM) and Torque Transfer from Polarization Vortices with the Electron Microscopy Pixel Array Detector

“…Here orbital angular momentum (OAM) functions as a toroidal order parameter in the polarization vortex arrays that could form the basis for memory storage and devices. Traditionally, electron microscopy methods for probing OAM have produced angular momentum dependent beams in the form of vortex beams [2][3], where the electron probe is divided into three separate beams each with angular momentum, +l, 0, and l, respectively. However, because of the division in intensity, signal to noise remains low.…”