Paris (AFP)
The Google study claiming to have experienced "quantum supremacy" with a processor capable of computing in three minutes instead of 10,000 years, which had leaked by mistake in September, was released Wednesday in the journal Nature.
This study was briefly posted on the NASA website, and revealed in the wake of the Financial Times on September 21, before being withdrawn.
A team of Google researchers describes how they managed to create a processor, called Sycamore, which manages to perform a calculation in 200 seconds, where a "classic" supercomputer would have put, according to their references, "about 10,000 years."
"This phenomenal acceleration compared to all known classical algorithms is an experiment of quantum supremacy", explain the researchers in Nature. This calculation, specific to this experiment, is according to them a "step on the way" of the universal quantum computer, highly anticipated in the computer world.
Sycamore managed to run a program with 53 qubits, the basic building block of quantum computing. Unlike conventional computer bits that can only be in two states, 0 or 1, qubits can be in multiple states at once. This superposition of states, the foundation of quantum physics, creates a "parallelism" that allows multiple calculations at once.
The manipulation of qubits is tricky because it is difficult to stabilize their quantum state - one needs simple atoms, cold, and totally isolated from the outside world.
"By taking this important step, we demonstrate that quantum acceleration is achievable in a real world, and that it is not confined to hidden physical laws," say Google researchers.
After the leak of this study, several experts had urged caution, saying that this specific calculation "was useless", and that the advent of a universal quantum computer was not for tomorrow. The latter, presented as a Grail, would notably be able, thanks to almighty algorithms, to break the so-called "RSA" cryptographic systems, currently used by global computing.
The information on Google came out when IBM, the other heavyweight very advanced in the quantum race, announced that it would put online, accessible to researchers and developers, a quantum machine of 53 qubits, the equivalent in power of the Google machine.
© 2019 AFP