Quantum device that can predict alternative futures created by scientists

Computer could 'scale without bound', say scientists

Andrew Griffin@_andrew_griffin
Tuesday 09 April 2019 14:46

Scientists have created a quantum device that allows them to predict alternative realities.

The complex computer is able to look at various "futures", allowing them to see the various possibilities that are available at any given moment.

While the computer is at the moment relatively limited, the researchers behind it say it could "scale without bound", and bring unimagined new possibilities.

Any decision could go a variety of different ways, and choosing one means picking from a whole array of different futures. The new device harnesses some of the most mysterious parts of our understanding of the universe to allow us to peak at those futures, seeing the possibilites that will follow from any one event.

For now, that does not mean being able to look into the future and see the lottery results. Instead, it focuses at the smallest scale, allowing the scientists to simulate 16 different timelines for most photons or packets of light.

But the quantum principles underlying the discovery could be applied at a much larger scale, they have noted, and are a demonstration of the vast and unknown possibilities that await in quantum computing.

Dr Mile Gu, one of the scientists from Nanyang Technical University (NTU) in Singapore, said: "When we think about the future, we are confronted by a vast array of possibilities.

"These possibilities grow exponentially as we go deeper into the future. For instance, even if we have only two possibilities to choose from each minute, in less than half an hour there are 14 million possible futures.

"In less than a day, the number exceeds the number of atoms in the universe."

His research group realised that, at a much smaller scale, a quantum computer can examine all possible futures of a decision process.

It does this by placing them in a quantum "superposition" - a kind of limbo in which different potential states occur simultaneously.

Only when the system is observed or disturbed does it "collapse" into one state or another.

This fundamental pillar of quantum mechanics was illustrated by the famous "Schroedinger's Cat" thought experiment, in which a cat is neither dead nor alive but a superposition of both states.

It also gave rise to the "many worlds" hypothesis - the idea that a myriad universes co-exist in parallel in which different fates are played out.

In the new study, potential future outcomes of a decision process were represented by the locations of photons.

The scientists showed that a superposition of multiple potential futures was weighted by the probability of one or other occurring when the system collapsed.

The machine has already demonstrated one application - measuring how much our bias towards a specific choice in the present impacts the future.

Lead researcher Farzad Ghafari, a PhD student at Griffith University in Australia, said: "Our approach is to synthesise a quantum superposition of all possible futures for each bias.

"Many current artificial intelligence (AI) algorithms learn by seeing how small changes in their behaviour can lead to different future outcomes, so our techniques may enable quantum enhanced AIs to learn the effect of their actions much more efficiently."

The study, published in the journal Nature Communications, was inspired by the late Nobel Laureate theoretical physicist Richard Feynman.

He was the first to realise that when a subatomic particle travels from point A to point B, it does not necessarily choose a single path. Instead, it simultaneously follows all the possible paths connecting the points.

Dr Jayne Thompson, a member of the Singapore team, said: "Our work extends this phenomenon and harnesses it for modelling statistical futures."

While the prototype device simulates no more than 16 futures, the underlying quantum algorithm could in principle "scale without bound", said the researchers.

Professor Geoff Pryde, who was in charge of the Griffiths group, said: "This is what makes the field so exciting.

"It is very much reminiscent of classical computers in the 1960s. Just as few could imagine the many uses of classical computers in the 1960s, we are still very much in the dark about what quantum computers can do."

Additional reporting by Press Association

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