UNSW scientists up coherence time of a spin-orbit quantum computing qubit in silicon

Meanwhile, D-Wave Systems has announced an expansion of its Leap service to India and Australia, allowing access to quantum computing in the cloud.
Written by Asha Barbaschow, Contributor

A team led by scientists from the University of New South Wales (UNSW) has announced "significantly" increasing the coherence time of a spin-orbit quantum bit (qubit) in silicon, allowing them to preserve quantum information for longer.

The ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), based out of UNSW, said the results open up a new pathway to make silicon quantum computers more scalable and functional.

"Spin-orbit qubits have been investigated for over a decade as an option to scale up the number of qubits in a quantum computer, as they are easy to manipulate and couple over long distances. However, they have always shown very limited coherence times, far too short for quantum technologies," a release from CQC2T explained.

The research shows that long coherence times are possible when spin-orbit coupling is strong enough. The scientists have demonstrated coherence times of 10,000x longer than previously recorded for spin-orbit qubits.

"We turned the conventional wisdom on its head by demonstrating exceptionally long coherence times -- ~10 milliseconds -- and therefore, that spin-orbit qubits can be remarkably robust," CQC2T chief Investigator and UNSW Professor Sven Rogge said.

See also: Australia's ambitious plan to win the quantum race

In explaining the breakthrough, CQC2T said the stability of a qubit determines the length of time that it can preserve quantum information. It said in spin-orbit qubits, information is stored on the spin of the electron as well as its motion.

"It is the strength of the coupling between these two spins that keeps the qubit stable and less prone to being destroyed by electric noise in devices," it said.

"The quantum information in most spin-orbit qubits is extremely fragile. Our spin-orbit qubit is special because quantum information stored in it is very robust," added Dr Takashi Kobayashi, who performed the research at UNSW and is now based out of Tohoku University in Japan.

"The information is stored in the orientation of the spin and orbit of the electron, not just the spin. The circular orbit of the charged electron and the spin are locked together like gears due to the very strong attraction in the spin-orbit coupling."

Kobayashi said increasing the strength of that spin-orbit coupling lets the team achieve significantly longer coherence times.

For a quantum computer to outperform a classical computer, a large number of qubits need to work together to perform complex calculations.

Real-time access to commercial quantum computing in the cloud

D-Wave Systems has announced an expansion of its Leap quantum cloud service to India and Australia, allowing developers, researchers, and businesses across both countries access to D-Wave 2000Q quantum computers, hybrid solvers, and the Quantum Application Environment (QAE).

The company is touting the service as real-time cloud access to a commercial quantum computer.

"Quantum computing is poised to fundamentally transform the way businesses solve critical problems, leading to new efficiencies and profound business value in industries like transportation, finance, pharmaceuticals and much more," D-Wave vice president of software and services Murray Thom said.

"The future of quantum computing is in the cloud. That's why we were eager to expand Leap to India and Australia, where vibrant tech scenes will have access to real-time quantum computers and the hybrid solver service for the first time, unlocking new opportunities across industries."

The total number of supported countries is now 37, with D-Wave touting over 200 early applications have been built with its systems.


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