Via KurzweilAI.net — This really is just amazing. A transistor made of one single atom of phosphorus.
Single-atom transistor created KurzweilAI.net, Dec. 7, 2009
A working transistor whose active region comprises only of a single phosphorus atom in silicon has been built byresearchers from Helsinki University of Technology, University of New South Wales, and University of Melbourne.
The device uses sequential tunneling of single electrons between the phosphorus atom and the source and drain leads of the transistor. The tunneling can be suppressed or allowed by controlling the voltage on a nearby metal electrode with a width of a few tens of nanometers.
The researchers plan to use the spin degree of freedom of an electron of the phosphorus donor as a quantum bit (qubit). They were able to observe spin up and down states for a single phosphorus donor in a magnetic field for the first time–a crucial step towards the control of these states in realizing a qubit.