Electron beams, like light, spread out when they pass through an opening. Even highly focused beams such as lasers spread over large distances, a result of the wave character of light. However, by manipulating the wave form near its source, researchers can create something known as an Airy beam, which doesn’t disperse—and in fact follows a curved path. A new experiment has created Airy beams using electrons, a significant step toward highly controllable electron beams. As a bonus, these beams can even “self-heal” after passing by a barrier.

Electrons also experience diffraction and interference, which is the source of the famous quantum double-slit experiment. In the new experiment, the researchers manipulated the wave function of an electron beam by sending it through a specific holographic pattern. They focused the beam using a magnetic field that acted much like a lens, producing a distinctive triangular bundle of electron beams. Each bundle followed a curved path, which the researchers determined by measuring the electron patterns at various distances from the hologram. [Read more…]

Electron, heal thyself! Making curved electron beams go around barriers

Metal tends to be opaque. However, if you perforate it with small holes in a certain pattern, it will still transmit some light—even if the holes are smaller than the wavelength of the light! This is known as extraordinary optical transmission (EOT), which has found uses in a number of devices since its discovery in the 1990s. However, a full understanding of the phenomenon has proven elusive. (That’s such a journalist way to put it, ain’t it?) A new experiment may have shown that the transmission is driven by two separate wave effects, and sorted out the role each plays in EOT.

Ordinarily, light can pass through an opaque barrier only if the barrier is pierced with openings larger than the light’s wavelength. (This also applies to all manner of waves, including sound and water waves.) That’s why EOT is fascinating: the holes are smaller than the wavelength, yet a substantial amount of light still gets through something that would ordinarily be opaque. Oddly, making the material thinner—and therefore more transparent—decreases the EOT effect. [Read more….]

Holey metal, Batman!