When electrons sing in harmony — and sense the shape of their home

Coherence Without Superconductivity

Quantum coherence—the ability of particles to move in synchrony like overlapping waves—is usually limited to exotic states such as superconductivity, where electrons pair up and flow coherently. In ordinary metals, collisions quickly destroy such coherence. But in the Kagome metal CsV₃Sb₅, after sculpting tiny crystalline pillars just a few micrometers across and applying magnetic fields, the MPSD team observed Aharonov–Bohm-like oscillations in electrical resistance. Thus showing that electrons were interfering collectively, remaining coherent far beyond what single-particle physics would allow. “This is not what non-interacting electrons should be able to do,” says Chunyu Guo, the study’s lead author. “It points to a coherent many-body state.”

A Shape-Sensitive Quantum State

Even more surprisingly, the oscillations depended on the crystal's geometry. Rectangular samples switched patterns at right angles, while parallelograms did so at 60° and 120°—exactly matching their geometry. “It’s as if the electrons know whether they’re in a rectangle or a parallelogram,” explains Philip Moll, the responsible MPSD Director. “They’re singing in harmony—and the song changes with the room they’re in.”

The discovery suggests a new way to control quantum states: by sculpting the geometry of a material. If coherence can be shaped rather than merely observed, researchers could design materials that behave like tuned instruments—where structure, not just chemistry, defines their resonance. “Kagome metals are giving us a glimpse of coherence that is both robust and shape-sensitive,” says Moll. “It’s a new design principle we didn’t expect.”

A broader resonance

The Kagome lattice has long intrigued scientists due to its intricate design of interwoven triangles and hexagons, which often geometrically frustrate electrons and give rise to exotic phases of matter. The recent findings by the Hamburg team extends this effects from the atomic level to the scale of devices, demonstrating that geometry influences the collective quantum behavior of electrons. Much like a choir resonates differently in a cathedral than in a concert hall, electrons in these star-shaped crystals seem to produce a new sound—one influenced not just by the arrangement of atoms but also by their shape. Currently, this phenomenon is limited to laboratory settings, where focused ion beams shape crystals into micrometer-sized pillars. However, the implications of this research are far-reaching. “Once coherence can be shaped rather than merely discovered, the frontier of quantum materials could shift from chemistry to architecture,” says Guo.”It opens a new avenue of designing quantum functionality for future electronics by reshaping material geometry.”