Switching an electrical current with atoms: the reproducible operation of a multi-atom relay

The demonstration of a multi-atom quantum point contact relay is reported, which can be reversibly switched between a quantized conducting ‘on-state’ and an insulating ‘off-state’ by applying an electrochemical control potential to a separate, third electrode, the control or gate electrode. The transition occurs directly from the conducting ‘on-state’ at 5 G0 (G0=2e2/h being the conductance quantum) to the insulating ‘off-state’. No stable intermediate levels are observed during the switching process, indicating a reproducible bistable reconfiguration of one single multi-atom contact rather than a deposition and dissolution of different parallel contacts. The results at the same time demonstrate the feasibility and reproducible operation of a configurable electronic device based on a multi-atom contact, which exhibits the functionality of an atomic relay or a transistor, opening intriguing perspectives for electronics and logics on the atomic scale.