The researchers have reported this missing piece in the journal Science Advances which we get for the spot the quantum boomerang competition.
Project leader Andrea Morello said that the whole thing was a bit like a Lego box – you can start building up a large architecture by piecing its components together.
Then we guess it breaks and you have a quantum bit on the floor which you tread on in the dead of night when you get up for a glass of water.
Morello and his colleagues have so far been perfecting its basic element, the “quantum bit”. This is a single phosphorus atom entombed in a silicon crystal. Using a carefully tuned magnetic field, the researchers can manipulate the atom’s quantum “spin”, flipping it up or down.
A quantum computer is “not just a ‘faster’ computer,” Morello says. “They are the equivalent of a jet plane to a bicycle.”
Last year the team showed they can write, read and store the spin of a single quantum bit with better than 99.99% accuracy using a magnetic field.
But to carry out complex calculations, a quantum computer needs thousands, or even millions of quantum bits, that can all be individually controlled.
In their latest work, carried out by experimental physicist Arne Laucht, Morello and his team found a way to control each quantum bit using a simple electrical pulse and flooding the whole device with a single magnetic field.
By timing their electrical pulses, the team can tune the phosphorus atom in and out of the oscillating magnetic field, and so flip the phosphorus atom’s spin into any position they want – up, down or an intermediate superposition – without affecting its neighbours.
Kane cautions that we are still a long way from large-scale quantum computing in silicon but he thinks that large-scale silicon quantum computing will become a reality, but there is still a long, steep road ahead.
The group is already at work on these challenges. Morello is confident they will have all the elements in place to build a small-scale test-system within 10 years.
No cats were harmed during testing.