Bend it like Schrödinger: Beams of electrons curve around barriers

The pattern produced by an Airy beam of light: one which doesn't spread out or grow fainter, and follows a curved trajectory. Researchers have now produced Airy beams of electrons.

American Physical Society

If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light. But, in 2007, researchers overcame that limit, and created curved beams of light that did not diffract by carefully shaping their waveform.

Now an experiment has used electrons' wave properties to create similar curved beams of electrons. Noa Voloch-Bloch, Yossi Lereah, Yigal Lilach, Avraham Gover, and Ady Arie sent electrons through a holographic film, which shaped their wave characteristics the same way that earlier experiments did for light. Without any additional force, the electrons followed parabolic trajectories while remaining in a tight beam. These paths even "healed" after passing obstacles, restoring their shape as though the objects were not there.

According to quantum physics, particles and waves are two aspects of the same system. The trajectory of a particle is actually governed by its quantum-mechanical wave function, which gives the probability for a particle may be found at a particular position. Waves traveling through an aperture, for example, will interfere with themselves, producing a gradually spreading beam where the particles follow diverging paths; that's diffraction. Lasers, flashlights, and the like send light through an opening, and so all they experience diffraction.