Quantum point-contact switches using silver particles

We have demonstrated a switching system with a quantized point contact using the silver particle motion. By applying appropriate bias voltages, the silver particles that are positioned between a scanning tunneling microscope tip and a substrate stick and unstick to the tip. The minute motion of the particles is induced by sum of two Coulomb interactions. The typical conductance of the contact formed is constant, which shows low integral multiples of quantized conductance. Reproducible switching cycles of the contact are achieved using continuous multiple square voltage pulses with a frequency up to $40kHz$⁠.