The finding, by a team led by Princeton physicist Jason Petta, could eventually allow engineers to build quantum computers consisting of millions of quantum bits, or qubits. So far, quantum researchers have only been able to manipulate small numbers of qubits, not enough for a practical machine.
“The whole game at this point in quantum computing is trying to build a larger system,” said Andrew Houck, an assistant professor of electrical engineering who is part of the research team.
To make the transfer, Petta’s team used a stream of microwave photons to analyze a pair of electrons trapped in a tiny cage called a quantum dot. The “spin state” of the electrons — information about how they are spinning — serves as the qubit, a basic unit of information. The microwave stream allows the scientists to read that information.
“We create a cavity with mirrors on both ends — but they don’t reflect visible light, they reflect microwave radiation,” Petta said. “Then we send microwaves in one end, and we look at the microwaves as they come out the other end. The microwaves are affected by the spin states of the electrons in the cavity, and we can read that change.”
In an ordinary sense, the distances involved are very small; the entire apparatus operates over a little more than a centimeter. But on the subatomic scale, they are vast. It is like coordinating the motion of a top spinning on the moon with another on the surface of Earth.
“It’s the most amazing thing,” said Jake Taylor, a physicist at the National Institute of Standards and Technology and the Joint Quantum Institute at the University of Maryland, who worked on the project with the Princeton team. “You have a single electron almost completely changing the properties of an inch-long electrical system.”
( via sciencedaily.com)