Editing Quantum tunnelling (section)

==== Scanning tunneling microscope ====
{{Main|Scanning tunnelling microscope}}

The scanning tunnelling microscope (STM), invented by [[Gerd Binnig]] and [[Heinrich Rohrer]], may allow imaging of individual atoms on the surface of a material.<ref name="Taylor" /> It operates by taking advantage of the relationship between quantum tunnelling with distance. When the tip of the STM's needle is brought close to a conduction surface that has a voltage bias, measuring the current of electrons that are tunnelling between the needle and the surface reveals the distance between the needle and the surface. By using [[Piezoelectric sensor|piezoelectric rods]] that change in size when voltage is applied, the height of the tip can be adjusted to keep the tunnelling current constant. The time-varying voltages that are applied to these rods can be recorded and used to image the surface of the conductor.<ref name="Taylor" /> STMs are accurate to 0.001&nbsp;nm, or about 1% of atomic diameter.<ref name="Knight" />