Australian engineers from the University of New South Wales (UNSW) were able to build a quantum bit that can remain in a stable superposition for ten times longer than was previously possible. As quantum computation largely depends on the stability of qubits, the new improved qubits should drastically improve the performance of future quantum computers.

Artist’s impression of a single-atom electron spin, hosted in a silicon crystal and dressed by an oscillating electromagnetic field

The Australian university seems to be at the very forefront of quantum computing research. The UNSW was also recently responsible for proving that it could build quantum chips in silicon, just as regular chips are. The research showed that one day quantum computation might not happen just in special computers that need liquid nitrogen cooling or high-end lasers, but also in mass-market devices such as our PCs and smartphones.

“Dressed” Qubits

The recent discovery, made by a team led by Professor Andrea Morello from the School of Electrical Engineering and Telecommunications at UNSW, brings silicon quantum computers much closer to reality. This is possible due to the invention of the new type of qubits called “dressed qubits,” which are qubits subjected to an electromagnetic shield to protect them from external interference.

“We have created a new quantum bit where the spin of a single electron is merged together with a strong electromagnetic field,” said Arne Laucht, a Research Fellow at the School of Electrical Engineering & Telecommunications at UNSW, and lead author of the paper. “This quantum bit is more versatile and more long-lived than the electron alone, and will allow us to build more reliable quantum computers,” he explained.

Quantum computers are not going to replace conventional computers. However, they should be capable of doing highly complex calculations, such as the design of a new drug or material, that are either many orders of magnitude slower, or even impossible, to execute on regular computers.

Electromagnetic Noise Protection

The new qubits last for 2.4 milliseconds before they are dephased, which is an order of magnitude longer than what was previously possible. The researchers achieved the goal by using an electromagnetic field that oscillates continuously and steadily at a high frequency, which cancels out any other disturbance with a different frequency.

Laucht said that the reason these “dressed” qubits are so much more resilient to external noise is because they control the quantum information by the frequency in the same way an FM radio is controlled. This is unlike the undressed qubits, which require turning the amplitude of the control fields on and off, just like with an AM radio. Because they can only be turned on and off, the undressed qubits are much more sensitive to external noise.

Quantum Race Accelerating

The race for making the first practical universal quantum computer seems to be speeding up lately. Google also promised to announce a 50-qubit quantum computer, and IBM recently gave developers access to its 5-qubit computer, too.

The jury is also still out on the usefulness of D-Wave’s own quantum annealing computer. For now, it has only shown to be good at making quantum annealing operations orders of magnitude faster compared to a single-core PC, but so far, these operations haven’t proven to be too useful.

The University of Waterloo also intends to build a 100-qubit quantum computer over the next seven years. There also seem to be more and more universities securing increased funding to construct quantum computing research laboratories, which should only accelerate how fast quantum computing