A team led by Princeton‘s Associate Professor of Physics Jason Petta has developed a new method that could eventually allow engineers to build a working quantum computer consisting of millions of quantum bits (qubits).
Quantum computers take advantage of the strange behaviors of subatomic particles like electrons. By harnessing electrons as they spin, scientists could use the particles to form the basis for a new type of computing.
The problem, though, is that these incredibly tiny electrons are hard to control. So far, scientists have only been able to harness extremely small numbers of them.
“The whole game at this point in quantum computing is trying to build a larger system,” said Andrew Houck, an associate professor of electrical engineering at Princeton who is part of the research team.
To transfer information 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.”