Optical transistors made from single molecules

ScienceDaily (July 3, 2009) - Researchers "ETH Zurich" has succeeded in making transistors from a single molecule optics. This has brought them one step closer to an optical computer.

Internet connection and a computer needs to be ever faster and more powerful now. However, conventional processing center unit (CPU / processor) to limit a computer's performance, for example because they generate lots of heat. Millions of transistors that switch and strengthen the electronic signal in the CPU is to be responsible. One centimeter square of the CPU can emit up to 125 watts of heat is more than ten times as much as one square centimeter of electric hotplate.

Photons, not electrons

This is why scientists have been trying for some time to find a way to produce integrated circuits that operate based on photons, not electrons. The reason is that photons do not only generate much less heat than electrons, but they are also very high data transfer speeds possible.

Although most part of the current telecommunication techniques based on optical transmission signals, the necessary encoding of the information generated by using an active electronic control. compact optical transistor is long dead. Sandoghdar Vahid, Professor of Physical Chemistry Laboratory of ETH Zurich, explains that, "Comparing the current state of electronic technology, we are rather close to the vacuum tube amplifier is around the fifties and 'integrated circuits' us today."
However, his research group that has been achieved by determining optical solutions made with a single molecule transistor. For this, they have used the fact that energy is quantized molecules; when the laser light is shot molecules in the ground state, light is absorbed. As a result, laser beam unquenchable. On the contrary, it is possible to release the absorbed energy again in the second target by floodlights. This happens because of changes in the quantum state of molecules, with the result that strengthens the light. This is called stimulated emission, Albert Einstein that explains more than 90 years ago, also form the basis for the principle of laser.

Focus on nano-scale

Jaesuk Hwang, the first scientific study author and member of the group Sandoghdar nano-optics, explaining that, "conventional laser amplification achieved in the large number of molecules." By focusing on a single laser on a small molecule, ETH Zurich researchers have been able to produce a stimulant emissions using only one molecule. They helped in this by the fact that, at low temperature, the molecules seem real increase surface area to interact with light. The researchers need a cooling molecules to below minus 272 degrees Celsius (minus 457.6 degrees Fahrenheit), which is one degree above absolute zero. In this case, extending the surface around the area related to the diameter of the focused laser.

Replacement of light by light

By using a laser to prepare the quantum state of one molecule in a controlled fashion, scientists can significantly weaken or strengthen the two lasers. This operation mode is identical to a conventional transistor, where the electric potential can be used to modulate the second signal.

Thus, components such as single molecule transistors could also pave the way for computer kuantum.Sandoghdar says, "Many years of research will be necessary before the change in electron photon Transistor.Sementara it, scientists will learn to manipulate and control quantum systems in a targeted, move them closer to the dream of a quantum computer. "