Measuring an electron beam's orbital angular momentum spectrum
arXiv:1609.09129
Abstract
Quantum complementarity states that particles, e.g. electrons, can exhibit wave-like properties such as diffraction and interference upon propagation. \textit{Electron waves} defined by a helical wavefront are referred to as twisted electrons~\cite{uchida:10,verbeeck:10,mcmorran:11}. These electrons are also characterised by a quantized and unbounded magnetic dipole moment parallel to their propagation direction, as they possess a net charge of ~\cite{bliokh:07}. When interacting with magnetic materials, the wavefunctions of twisted electrons are inherently modified~\cite{lloyd:12b,schattschneider:14a,asenjo:14}. Such variations therefore motivate the need to analyze electron wavefunctions, especially their wavefronts, in order to obtain information regarding the material's structure~\cite{harris:15}. Here, we propose, design, and demonstrate the performance of a device for measuring an electron's azimuthal wavefunction, i.e. its orbital angular momentum (OAM) content. Our device consists of nanoscale holograms designed to introduce astigmatism onto the electron wavefunctions and spatially separate its phase components. We sort pure and superposition OAM states of electrons ranging within OAM values of and . We employ the device to analyze the OAM spectrum of electrons having been affected by a micron-scale magnetic dipole, thus establishing that, with a midfield optical configuration, our sorter can be an instrument for nano-scale magnetic spectroscopy.
5 pages, 3 figures, 3 pages of supplementary materials
References in corpus (15)
- Entanglement of Orbital Angular Momentum States of Photons
- Efficient separation of the orbital angular momentum eigenstates of light
- Semiclassical Dynamics of Electron Wave Packet States with Phase Vortices
- Relativistic Electron Vortex Beams: Angular Momentum and Spin-Orbit Interaction
- Magnetic monopole field exposed by electrons
- Electron vortex beams in a magnetic field: A new twist on Landau levels and Aharonov-Bohm states
- Quantised orbital angular momentum transfer and magnetic dichroism in the interaction of electron vortices with matter
- Sculpturing the Electron Wave Function
- Limitations to the determination of a Laguerre-Gauss spectrum via projective, phase-flattening measurement
- Imaging the dynamics of free-electron Landau states
- Measuring the orbital angular momentum of electron vortex beams using a forked grating
- A novel vortex generator and mode converter for electrons
- Is magnetic chiral dichroism feasible with electron vortices?
- Measuring the Orbital Angular Momentum of Electron Beams
- Local orbital angular momentum revealed by spiral phase plate imaging in transmission electron microscopy