Quantum computing researchers achieve control over individual electrons
February 9, 2010
The superfast computers of tomorrow will likely be able to manipulate individual electrons, harnessing their charge and magnetism to achieve massive data storage and outstanding processing speeds at very low power requirements. But how exactly do you go about manipulating single electrons independently, without affecting the ones nearby? Princeton University's Jason Petta has recently demonstrated a way to do just that in a breakthrough for the field of spintronics that brings faster and low-power number-crunching closer to reality.
Qubits, or "quantum bits," are the analogue of a classical bit in quantum computing. They possess some unique properties, such being able to assume multiple values ("0" and "1") at the same time, and they can also be represented by a single subatomic particle, which truly opens up new horizons as far as miniaturization is concerned.
In previous experiments, researchers would usually resort to using microwave radiation to manipulate a very large number of electrons that, taken together, form a single quantum bit. Doing so can, however, impair performance, as we've seen in some of the early prototypes of spintronics processors we've covered at Gizmag. Perhaps even more importantly, being able to manipulate individual electrons rather than large groups of them would have very dramatic effects in terms of power consumption, and effectively could one day boost the battery life of portable electronics in ways that are hard to even conceive.
Assistant professor of physics, Jason Petta, at Princeton has demonstrated a technique to isolate one or two electrons at a time and managed to control their behavior by purely electrical means, as detailed in a paper published on last week's edition of the journal Science.
The electrons are located in corrals that are created when a voltage is applied to minuscule electrodes, forming individual qubits. These qubits are cooled to temperatures nearing absolute zero and trapped between two of these corrals on the surface of a chip made of gallium arsenide — a semiconductor with properties similar to silicon. The depth of each well can be controlled by adjusting the voltage applied on the electrodes, and individual electrons can be moved from one well to the other simply by toggling the voltages of the two electrodes.
"We are still at the level of just manipulating one or two quantum bits, and you really need hundreds to do something useful," Petta commented. Still, his research is undeniably a very significant step forward that opens the door to high-performance quantum computing.
The research was supported by the Sloan Foundation, the Packard Foundation and the National Science Foundation.