Professor Mile Gu, an expert from the Faculty of Mathematical and Physical Sciences at Nanyang Technological University (NTU) in Singapore, has two great passions: the ancient game of strategy go and quantum mechanics; specifically, how to take advantage of this discipline, which studies what happens to matter at minute scales, to try to simulate particularly complex processes and correlations. And if there is one that is, it is the way the future is built.
“When we think about what is to happen, we are faced with an immense amount of possibilities. What’s more, their number increases exponentially as we move into the future. Let’s imagine that we could only choose between two options every minute. Well, in less than half an hour fourteen million possible futures would have been generated; before a day passes, their number would exceed the number of atoms in the entire universe “, explains this scientist. The question is: would it be possible to anticipate them in any way?
Gu and a group of collaborators from the aforementioned Asian institution realized that they could examine all these futures with a special algorithm if they were able to place them in a state of quantum superposition. This fundamental principle of quantum mechanics maintains that a physical system can exist in several states at the same time – a photon, for example, would exist simultaneously as a wave and a particle – but when it is measured it is specified in one of them. In 1935, the physicist Erwin Schrödinger proposed a thought experiment that, since then, is often used to try to understand how it is possible for something to be present in several states at the same time, which, clearly, seems nonsense.
Schrödinger’s cat again
In such an essay, known simply as “Schrödinger’s cat”, he proposes that we imagine one of these felines locked in a box. In it, there are two containers: one contains food and the other a lethal poisonous compound. The cat will end up trying one or the other, so depending on what it does, it will be dead or alive. But from the quantum point of view, the animal will be in both states at the same time – the aforementioned superposition – at least until someone opens the box and observes what has happened, at which point one of the possibilities is realized.
The team led by Gu contacted scientists from the Center for Quantum Dynamics at Griffith University, in Australia, to try to determine whether it was possible to develop a device capable of managing the possible futures that would emanate from decision-making. Together they devised a processor that uses the location of photons to represent all of those options, so their state is, in essence, a superposition of multiple potential futures, valued based on the probability that they can happen.
“Its operation is inspired by the work of theoretical physicist Richard Feynman,” says Jayne Thompson, from NTU, who has participated in this initiative in a statement. “Feynman, who won the Nobel, realized that when a particle travels from point A to point B it does not have to follow a single path. On the contrary, it travels simultaneously all the possible routes that connect both points. Our work takes advantage of this phenomenon to be able to model statistical futures ”, he adds. In fact, ingenuity already allows us to measure the impact of our predisposition to choose a certain option.
An improved AI
Physicist Farzad Ghafari, a co-author of the study, says that when these overlaps interfere with each other, you can avoid completely observing each future individually. “Many artificial intelligence (AI) systems learn when they detect how small changes end up producing very different results; our approach may allow quantum-enhanced AI to recognize the effects of its actions in a much more efficient way, “he says.
At the moment, the aforementioned prototype simulates sixteen futures simultaneously, but, in the opinion of the researchers, the quantum algorithm that it uses could, in theory, manage all possible options, without any limit.
Referencia: Interfering trajectories in experimental quantum-enhanced stochastic simulation. Farzad Ghafari et al. Nature Communications (2019).
