Building block for quantum computer easier to manipulate
Researchers from FOM, the Kavli Institute of Nanoscience at Delft University of Technology, and Eindhoven University of Technology have developed techniques that make it far easier to manipulate the building blocks of a future, superfast quantum computer. Now they can manipulate these building blocks (qubits) with electrical fields instead of magnetic fields, as was common practice to date. And they have also found a way of incorporating these qubits into semiconductor nanowires. The researchers published their findings in the journal Nature on Thursday 23 December.
Spin
A qubit is the building block of a possible, future quantum computer. Such a computer would be much faster than current computers. A qubit can be made by trapping a single electron in a semiconducting material. Just like a normal computer bit, a qubit can assume the states '0' and '1'. In a qubit this is achieved using the spin of the electron. This spin is caused by the electron rotating on its own axis. This rotation takes place in two directions (which thus represent the '0' state and the '1' state).
Electrical instead of magnetic
Up until now, the spin of an electron was controlled using magnetic fields. But these fields are very difficult to generate on a chip. However, the electron spin in the qubits produced by the Dutch scientists can be controlled by a potential difference or an electric field. This type of control has major advantages. FOM workgroup leader Professor Leo Kouwenhoven, researcher at the Kavli Institute of Nanoscience at Delft University of Technology: 'These spin-orbit qubits combine the best of both worlds: the advantages of electronic control and those of information storage in the electron spin.'
Nanowires
The Dutch research has produced another important innovation. The scientists managed to incorporate two qubits into nanowires made from a semiconducting material (indium-arsenide). These wires have a diameter of just several nanometres and are only a few micrometers in length. Kouwenhoven: "These nanowires are increasingly being used as handy building blocks in nanoelectronics. For example, nanowires are a superb platform for quantum information processing."
Further information
Prof. Leo Kouwenhoven, Professor of Quantum Transport, Kavli Institute of Nanoscience, Delft University of Technology, telephone: +31 (0)15 278 6064.
Ineke Boneschansker, Science Information Officer, Delft University of Technology, telephone +31 (0)15 278 8499.
Reference
S. Nadj-Perge, S.M. Frolov, E.P.A.M. Bakkers & L.P. Kouwenhoven (2010) Spin-Orbit qubit in a semiconductor nanowire. Nature 468, 1084 – 1087.