Quantum Point Contact Switches

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Science  21 Jul 1995:
Vol. 269, Issue 5222, pp. 371-373
DOI: 10.1126/science.269.5222.371


Switching behavior between electron tunneling and ballistic transport states was induced by repeatedly bringing a sharpened nickel wire into contact with a gold surface. The high-conductivity ballistic state had a quantized conductance of 0.977 ± 0.015 (2e2/h). Switching was accomplished by moving the electrodes with a piezoelectric actuator over a distance of 2 angstroms. The two electrodes and the actuator form a three-terminal device that is demonstrated to be a reliable digital and analog switch; it shows good discrimination between high and low states and possesses the important property of power gain. The conductance channel is most likely only one atom wide and possibly consists of a single atom.