‘Google claims it has reached quantum supremacy’

According to the FT, Google claims that it has performed a calculation with a quantum processor that the most powerful classical computers cannot process in practice. This would have reached the point of so-called quantum supremacy.

Google’s quantum processor could perform the calculation in three minutes and twenty seconds, whereas the Summit supercomputer would take about ten thousand years. The breakthrough would have been achieved with Sycamore, a quantum system with 53 qubits. That would be stated in a research paper from Google that appeared briefly on a NASA website. The document has been removed, but the Financial Times has seen this. The US Department of Energy’s IBM Summit computing cluster is the world’s fastest supercomputer with performance of 143.5 petaflops and peak performance of 200.8 petaflops.

It would be a technically complex calculation without any practical use. “To our knowledge, it is the first computation that can only be performed on a quantum processor,” the document said. Furthermore, the Google scientists would admit that the moment when quantum systems can be used for solving practical problems will be many years away. On the other hand, they expect the power of quantum computers to increase ‘double exponentially’ every year. Moore’s law for traditional computing can be interpreted as the transistor density of chips doubling every two years, which for a long time led to exponential growth in the computing power of CPUs.

Details about the calculation and the quantum system used are not known and it is also unclear whether and if so when a definitive publication will follow. Google wrote in 2017 that it assumed that quantum computers from 50 qubits can handle calculations that classical computers cannot process. Like Google, IBM has a 53-qubit system ready.

Until now, researchers frequently use classical computer systems to simulate quantum systems, but from a certain point the computing power of a quantum computer becomes too great to be able to simulate. That point is called quantum supremacy. The challenge is to keep the quantum systems stable for practical calculations when increasing the number of qubits. According to skeptics, it could be decades before quantum systems can be used in practice.

More on this topic can be found in the background article The Race to a Quantum Computer – Will Google, IBM or Microsoft Win?.

Source: John Martinis of Google: Quantum Computing and Quantum Supremacy.