Tokyo Team Recreates the Double-Slit Experiment at Atomic Scale to Read Atom Vibrations

Controlling heat has become a bigger challenge as the semiconductors inside smartphones and computers grow more powerful and more miniaturised, because the way heat moves through a material is governed by how its atoms vibrate, something that has been hard to observe directly at the atomic scale. A team at the University of Tokyo, led by professor Naoya Shibata with JSPS research fellow Koudai Tabata, has now managed to read out how neighbouring atoms vibrate together by recreating the classic double-slit experiment at atomic scale. The work is published in the journal Nature.

The double-slit experiment, first performed with light by British physicist Thomas Young in the early 19th century, shows the wave nature of light through the pattern of bright and dark fringes created when waves overlap after passing through two narrow slits. Shrinking that experiment to the atomic scale, so it could reveal the arrangement and motion of atoms at the level of a single atomic bond, had never been achieved before.

The Tokyo team focused an electron beam, narrowed by a scanning transmission electron microscope, onto the gap between two neighbouring silicon atomic columns just 136 picometres apart, about seven orders of magnitude smaller than Young's original setup, and found the pair of atoms behaved like a double slit for the electrons. By closely examining the resulting fringe pattern, the researchers could read out how much the neighbouring atoms vibrate in the same direction, a new way to probe the strength of the bond between them and how heat moves through the material.

The technique gives a way to study phonons, the lattice vibrations that affect how rigid an atomic bond is and how efficiently it conducts heat, one atomic bond at a time. Applied to semiconductor materials, the researchers say the method could eventually help identify, at the atomic level, where heat tends to accumulate or struggles to flow, informing the design of better heat dissipation in semiconductor devices.