The tech giant has revealed how quantum computers are capable of beating the best supercomputers.
According to a new study, Google researchers claimed that they have found conditions under which quantum computers can beat their classical counterparts.
They also claimed that quantum machines have a noise threshold that classical machines cannot beat.
Quantum-computer processor Sycamore used to run RCS
Published in the journal Nature, the study used a quantum computer processor named Sycamore to run random circuit sampling (RCS), a simple quantum algorithm that essentially generates a random sequence of values.
The team analyzed Sycamore’s output and found that when it ran in a mode with a lot of noise interference while performing RCS, it could be ‘spoofed’, or beaten, by classical supercomputers. But, when the noise was lowered to a certain threshold, Sycamore’s computation became complex enough that spoofing it was effectively impossible — by some estimates, it would take the fastest classical supercomputer in the world ten trillion years, reported Nature.
Researchers implemented an RCS algorithm
“By implementing an RCS algorithm we demonstrate experimentally that there are two phase transitions observable with Cross-Entropy Benchmarking (XEB), which we explain theoretically with a statistical model. The first is a dynamical transition as a function of the number of cycles and is the continuation of the anti-concentration point in the noiseless case,” said researchers in their study.
Researchers claimed that the second is a quantum phase transition controlled by the error per cycle; to identify it analytically and experimentally, they created a weak link model that allows varying the strength of noise versus coherent evolution, according to their research published in the pre-print server arXiv.
“Furthermore, by presenting an RCS experiment with 67 qubits at 32 cycles, we demonstrate that the computational cost of our experiment is beyond the capabilities of existing classical supercomputers, even when accounting for the inevitable presence of noise. Our experimental and theoretical work establishes the existence of transitions to a stable computationally complex phase that is reachable with current quantum processors,” said researchers in their study.
Sycamore processor is fabricated to control electrons
Almost similar to the silicon chips, the Sycamore processor is specially fabricated to control the electrons that flow through it with quantum precision.
The chip is kept at ultracold temperatures near absolute zero in an attempt to reduce temperature fluctuations that would destroy the electrons’ delicate states and introduce noise.
However, it is also claimed that Google’s latest results do not mean that quantum computers will replace classical computers.
For instance, Sycamore cannot perform typical operations of a regular computer, such as storing photos or sending e-mails. “Quantum computers are not faster—they’re different,” says Sergio Boixo, the head of Google’s quantum computing effort in Santa Barbara, California. According to Nature, they are intended to eventually do classically impossible—and useful—tasks, such as exactly simulating chemical reactions.