Researchers achieve electrical control of quantum bits, paving the way for quantum computers

Image: Arne Laucht

For the first time ever, researchers have encoded quantum information using simple electrical pulses.

Researchers from UNSW in Australia are a big step closer to creating affordable, large quantum computers, after gaining electrical control of quantum bits, or qubits, for the first time.

The team was able to store quantum information in silicon using only simple electrical pulses, instead of pulses of oscillating magnetic fields. This is the same way that the computers we use today encode data, and it means that we now have the ability to cheaply and easily control the quantum computers of the future.

"We demonstrated that a highly coherent qubit, like the spin of a single phosphorus atom in isotopically enriched silicon, can be controlled using electric fields, instead of using pulses of oscillating magnetic fields," said lead author of the study, Arne Laucht from UNSW Engineering, in a press release.

This is something that researchers have been attempting since 1998, and the results have now been published in the open-access journal Science Advances. 

The method works by distorting the shape of the electron cloud attached to the phosphorous atom, quantum engineer Andrea Morello, who also worked on the research, explained in the release.

"This distortion at the atomic level has the effect of modifying the frequency at which the electron responds," he said.

"Therefore, we can selectively choose which qubit to operate. It's a bit like selecting which radio station we tune to, by turning a simple knob. Here, the 'knob' is the voltage applied to a small electrode placed above the atom."

The research suggests that it will be possible to locally control data in a large-scale quantum computers using only inexpensive voltage generators, as opposed to the pricey high-frequency microwave sources that quantum researchers have used to encode information in the past.

It also means that these types of qubits can be manufactured using technology similar to the kind we currently use, which will greatly cut the cost of quantum computers.

The key to the team's success was embedding the phosphorous atom in a thin layer of purified silicon that contains only the silicon-28 isotope, which is non-magnetic and doesn't disturb the qubit.

The UNSW Engineering quantum group was the first in the world to demonstrate single-atom spin qubits in silicon back in 2012, and they also last year showed that they could control these qubits with 99 percent accuracy. Their overall goal is to build the world's first affordable, large-scale quantum computer, and we honestly can't wait.

Love engineering? Find out more about the world-leading research happening at UNSW Engineering.

ORIGINAL: Science Alert

FIONA MACDONALD

11 APR 2015