Quantum bit sustained 10 times longer than before allowing more quantum computing calculations to be performed

10/18/2016 - 13:59

Wilson Da Silva | Image: UNSW

Engineers at the University of New South Wales (UNSW) have created a new quantum bit that remains in a stable superposition for 10 times longer than previously achieved, dramatically expanding the time during which calculations could be performed in a future silicon quantum computer.

It’s another first for the diverse UNSW team that is leading the world in the ‘space race of the 21st century’.

The new quantum bit, made up of the spin of a single atom in silicon and merged with an electromagnetic field – known as ‘dressed qubit’ – retains quantum information for much longer that an ‘undressed’ atom, opening up new avenues to build and operate the superpowerful quantum computers of the future.


Ref: A dressed spin qubit in silicon. Nature Nanotechnology (17 October 2016) | DOI: 10.1038/nnano.2016.178


Coherent dressing of a quantum two-level system provides access to a new quantum system with improved properties—a different and easily tunable level splitting, faster control and longer coherence times. In our work we investigate the properties of the dressed, donor-bound electron spin in silicon, and assess its potential as a quantum bit in scalable architectures. The two dressed spin-polariton levels constitute a quantum bit that can be coherently driven with an oscillating magnetic field, an oscillating electric field, frequency modulation of the driving field or a simple detuning pulse. We measure coherence times of T*2p=2.4 ms_ and _THahn2p=9 ms , one order of magnitude longer than those of the undressed spin. Furthermore, the use of the dressed states enables coherent coupling of the solid-state spins to electric fields and mechanical oscillations.