Using electric fields rather than magnetic ones to control the spin of an electron, researchers in the Netherlands have developed a new flavour of qubit in an Indium Arsenide nanowire. The new approach could one day play a part in quantum cryptography, according to Nature.com.
The researchers have exploited 'the innate link between an electron's spin and its orbit around the nucleus' to exert finer control over the spin state of individual electron than is easily achievable using magnetic fields.
The changing electric field affects the orbit of an electron around the atomic nucleus, which in turn affects the static magnetic field created by the moving charges of the nucleus and electron. This can change the spin of an orbiting electron, so physicists have dubbed the phenomenon: spin-orbit interaction.
From Nature.com: In their experiment, [Leo Kouwenhoven and his colleagues at the Delft University of Technology] used a nanowire of indium arsenide (InAs), a semiconductor with heavy, highly-charged atomic nuclei that promote a strong spin–orbit interaction. The researchers applied voltages across five narrow gates surrounding the nanowire to isolate two electrons, which acted as two qubits. By then applying electric field pulses between gates and along the nanowire, they could alter the spin of the qubits from parallel (for example, up and up) to antiparallel (up and down).
Despite the fact that the duration of the spin-orbit link is shorter than has been demonstrated before, using Gallium Arsenide, the fact that the researchers have used a nanowire makes the research a little more intriguing. Nanowires have been used recently to make LEDs, and that suggests (with more work, naturally) optical circuits and applications in quantum cryptography.
More at Nature.com here.