A new valve for quantum matter: Steering chiral fermions by geometry alone

Researchers at Max Planck Institutes have demonstrated a chiral fermionic valve that spatially separates quantum particles by chirality using quantum geometry alone, without requiring magnetic fields or materials. The device, built from PdGa topological semimetal crystals, deflects fermions of opposite chirality into different paths by exploiting the quantum geometry of electronic wavefunctions. The team observed quantum interference of chiral currents over distances exceeding 15 micrometers and demonstrated electrical control of current-induced orbital magnetization. This breakthrough establishes a new control mechanism for quantum particles and opens pathways toward chiral quantum electronics where information is encoded using the handedness of quantum states.