The creation and demonstration of this logic-performing circuit within a single molecule may lead to smaller and faster computers that consume less power (I.B.M. Creates a Tiny Circuit Out of Carbon). The researchers at IBM made a "voltage inverter" - one of the three fundamental logic circuits that are the basis for all of today's computers - from a carbon nanotube, a tube-shaped molecule of carbon atoms that is 100,000 times thinner than a human hair.
This is the second breakthrough for the team using carbon nanotubes to make electronic devices, after in April, they were the first to produce arrays of carbon nanotude transistors, bypassing the need to separate metallic and semiconducting nanotubes. In binary, a voltage inverter changes a "1" into a "0" and a "0" into a "1." The researchers encoded he entire inverter logic function along the length of a single carbon nanotube, forming the world's first intra-molecular logic circuit.
As seen here, it is the design of an intra-molecular logic gate. Single carbon nanotube (shaded in blue) is positioned over gold electrodes to produce two p-type carbon nanotube field-effect transistors in series. A window is opened by e-beam lithography to expose part of the nanotube. The results show red circles (raw data for five different measurements on the same device; V=±2V), blue lines (average of the five measurements), and a thin straight line corresponding to the output/input of one.
The team also discovered that in addition to converting an entire nanotube from p-type to n-type, they could selectively convert part of a single nanotube to n-type, leaving the remaining part of the single nanotube p-type. This process was used to build the world's first single-molecule logic circuit.
Also, the output signal is stronger than the input. This development called "gain" is crucial to assemble gates and other circuit elements into microprocessors. Circuits with a gain less than one are useless and is so faint, it cannot be detected. IBM's circuit gain is 1.6, hopeful that more complex circuits could be made in the same manner.
Check out the full report conducted at the IBM Research Division in New York.