Single-Atom Transistor to Advance Quantum Computing

Experts at the Helsinki University of Technology, in Finland, the University of New South Wales, in Australia, and the University of Melbourne announce the development of a single-atom transistor. The component works by sequentially channeling a flow of electrons through the same phosphorus atom, the team says. The atom is encased in silicon in order for it to work, and the experts say that the approach could soon replace existing transistors, or even facilitate the development of quantum computers, PhysOrg reports.

“About half a year ago, I and one of the leaders of this research, professor Andrew Dzurak, were asked when we expect a single-atom transistor to be fabricated. We looked at each other, smiled, and said that we have already done that. In fact, our purpose was not to build the tiniest transistor for a classical computer, but a quantum bit which would be the heart of a quantum computer that is being developed worldwide,” Dr. Mikko Mottonen, an expert from the HUT, explains. He adds that shrinking existing transistors further down leads to the appearance of so-called quantum mechanical effects.

These effects occur when scientists try to reduce the size of a transistor already at the nanoscale even further. Inconsistencies appear and gradually increase as size decreases. This is very bad for normal transistors, but can be a beneficial thing for qubits, the basic units inside quantum computers. The classically irrational behavior provides the qubit's foundations, and allows for it to store more values than a normal transistor. Rather than operating on “1s” and “0s,” qubits also include the “1 and 0” value, which basically allows them to exist in two states at the same time.

What the new collaboration wants to accomplish is the use of the spin degree of freedom that electrons going through phosphorus atoms have to create a qubit. The scientists argue that the first steps have already been taken, and that they have already observed “up” and “down” spins in these electrons, for the first time. They argue that increased control over these phenomena could finally allow for the construction of a stable qubit, which is something many research groups have tried to do and failed.