Scientists at the University of Sydney have demonstrated the ability to predict how quantum systems will change and then prevent the system from breaking down.

This capability to "see" into the future is being hailed as a major achievement that could help bring the strange but powerful world of quantum technology closer to reality.

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A significant obstacle to building reliable quantum technologies such as quantum computers (which are far more powerful than digital computers) has been the phenomenon called "decoherence," or the randomization of quantum systems by their environments that effectively destroys the useful quantum character.

University of Sydney physicists took a technical quantum leap in addressing decoherence, and used techniques from big data to predict how quantum systems will change. This gave them the ability to prevent a system's from breaking down.

"Much the way the individual components in mobile phones will eventually fail, so too do quantum systems," said the paper's senior author Professor Michael J. Biercuk.

"But in quantum technology the lifetime is generally measured in fractions of a second, rather than years."

Prof. Biercuk said his group had demonstrated it was possible to suppress decoherence in a preventive manner. The key was to develop a technique to predict how the system would disintegrate.

He noted the immense challenges of making predictions in a quantum world.

"Humans routinely employ predictive techniques in our daily experience. For instance, when we play tennis we predict where the ball will end-up based on observations of the airborne ball," he said.

"This works because the rules that govern how the ball will move, like gravity, are regular and known. But what if the rules changed randomly while the ball was on its way to you? In that case it's next to impossible to predict the future behavior of that ball.

"And yet this situation is exactly what we had to deal with because the disintegration of quantum systems is random. Moreover, in the quantum realm observation erases quantumness, so our team needed to be able to guess how and when the system would randomly break.

"We effectively needed to swing at the randomly moving tennis ball while blindfolded."

The team turned to machine learning for help in keeping their quantum systems -- qubits realized in trapped atoms -- from breaking.

What might look like random behavior actually contained enough information for a computer program to guess how the system would change in the future. It could then predict the future without direct observation, which would otherwise erase the system's useful characteristics.

The predictions were remarkably accurate, allowing the team to use their guesses preemptively to compensate for the anticipated changes.

Doing this in real time allowed the team to prevent the disintegration of the quantum character, extending the useful lifetime of the qubits.

"We know that building real quantum technologies will require major advances in our ability to control and stabilize qubits - to make them useful in applications," said Prof.  Biercuk.

"Our techniques apply to any qubit, built in any technology, including the special superconducting circuits being used by major corporations.

"We're excited to be developing new capabilities that turn quantum systems from novelties into useful technologies. The quantum future is looking better all the time."

The applications of quantum-enabled technologies are compelling and already demonstrating significant impacts, especially in the realm of sensing and metrology. And the potential to build exceptionally powerful quantum computers using quantum bits, or qubits, is driving investment from the world's largest companies.

This research was published in the peer-reviewed journal, Nature Communications.

TagsUniversity of Sydney, quantum systems, Quantum, decoherence, Professor Michael J. Biercuk