Quantum Leap: Researchers have controlled the position of a single electron in a silicon circuit.

An international team of researchers has shown that it can control the quantum state of a single electron in a silicon transistor--even putting the electron in two places at once. Their discovery could help pave the way toward a practical quantum computer.

Quantum computers take advantage of the strange properties of subatomic particles to perform certain types of calculations much faster than classical computers can. Researchers are exploring a host of different approaches to quantum computing and some have even built primitive quantum circuits that can perform calculations. But practical quantum computing would require the ability to manufacture devices with millions of quantum circuits--rather than the 12 or 16 achievable now--that can be integrated with more-conventional electronics.

One theoretical approach to practical quantum electronics is to use conventional electronics--tiny semiconductor transistors--to control the state of a quantum system. Researchers led by Sven Rogge, a researcher at Delft University of Technology, in the Netherlands, performed the first practical experiments to verify the approach's theoretical predictions. The team--which also included researchers from Purdue University; the University of Melbourne, in Australia; and IMEC, in Belgium--found that it could control the quantum state of a single electron simply by altering the voltage applied to a transistor. "This represents a nice step towards future devices where performance is determined by manipulation of quantum states of single atoms," says Thomas Schenkel, a scientist at Lawrence Berkeley National Laboratory.