Schematic of a snowflake-like Vicsek fractal lattice used to trap electrons under a magnetic field. Credit: Biplab Pal
Electrons can be completely trapped within fractal structures using precisely tuned magnetic fields — a quantum effect with possible applications in computing and information processing1.
Fractals, found in ferns, snowflakes and blood vessels, repeat similar patterns at every scale. By simulating electron behaviour in an artificially designed quantum fractal lattice, Biplab Pal at Nagaland University has shown that Aharonov–Bohm (AB) caging — where a magnetic field halts electron motion through destructive interference — also arises in complex geometries such as the Vicsek snowflake.
The interference collapses the electron’s energy spectrum, blocking transmission across the fractal. Remarkably, the caging effect persisted even when the lattice was imperfect, suggesting robust control of electron motion.
Such resilience, Pal says, could enable precise manipulation of quantum states for memory and logic devices. AB caging had previously been observed only in simple 1D and 2D crystalline lattices. “This work shows that non-crystalline, amorphous materials can also be effectively used to design nanoelectronic quantum devices,” he adds.
