Doubts over Google's 'quantum supremacy' claim

Scientists at the World Laureates Forum expressed doubts about the “quantum supremacy” claim made by Google and if its quantum computer was really a quantum computer.

In a scientific paper last week, Google made a claim that it has achieved “quantum supremacy,” an experimental demonstration of the superiority of a quantum computer over a traditional one.

“There is very strong competition in the field of quantum computing,” said Serge Haroche, a 2012 Nobel Prize winner in physics.

“One difficulty is decoherence. In fact the quantum system is very fragile and the quantum superposition is easily destroyed. So for a real quantum computer to work, you have to make quantum error corrections, to be able to detect all the errors and to correct the errors. For the time being nobody knows how to implement effective error corrections,” Haroche said.

He believes that what the Google machine and all related machines are doing is trying to do computation with a limited number of particles without quantum error correction.

It’s very interesting but is not quantum computer, Haroche described Google’s quantum computer.

Classic computers store 1 or 0 in a “bit,” while a quantum computer uses qubit (quantum bit) to store a combination of 1s and 0s. One qubit holds two values, two qubits four, three qubits eight. Thus its computing power is exponentially greater than that of “bits.”

Companies and innovators are now working on possible applications, such as quantum GPS or quantum solutions to overcrowded subway stations.

It is not the time to celebrate or to say it had be done by quantum computing, he said.