Researchers from Nanyang Technological University, Singapore (NTU Singapore) and Griffith University in Australia have created a prototype quantum device that can generate all possible futures in a simultaneous quantum superposition.

If that sounds familiar you might be thinking of the scene in the 2018 film Avengers: Infinity War, where Dr. Strange looks into 14 million possible futures to search for a single timeline in which the heroes would be victorious.

“When we think about the future, we are confronted by a vast array of possibilities,” explains Assistant Professor Mile Gu of NTU Singapore, who led the development of the quantum algorithm that underpins the prototype. “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.”

## Ambitious experiment ready to be scaled up

The researchers realized they could use a quantum computer to examine all possible futures by placing them in a quantum superposition.

The quantum superposition is something similar to the infamous Schrödinger cat, which is simultaneously alive and dead. Gu and his research team from Singapore joined up a group of experimental scientist from Griffith University. Led by Professor Geoff Pryde at Griffith University to test their theories.

Together the two teams implemented a specially devised photonic quantuminformation processor in which the potential future outcomes of a decision process are represented by the locations of photons aka quantum particles of light.

The ambitious researchers then demonstrated that the state of the quantum device was a superposition of multiple potential futures, weighted by their probability of occurrence.

## Inspired by Feynman

“The functioning of this device is inspired by the Nobel Laureate Richard Feynman,” says Dr. Jayne Thompson, a member of the Singapore team.

“When Feynman started studying quantum physics, he realized that when a particle travels from point A to point B, it does not necessarily follow a single path. Instead, it simultaneously transverses all possible paths connecting the points. Our work extends this phenomenon and harnesses it for modeling statistical futures.”

The team says that their current prototype can simulate at most 16 futures simultaneously, but that the underlying quantum algorithm can in principle scale without bound. “This is what makes the field so exciting,” says Pryde.

“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. Each discovery of a new application provides further impetus for their technological development.”

The research has been published in the journal Nature Communications.