Quantum Computers Vastly Outperform Supercomputers When It Comes to Energy Efficiency
(PhysicsWorld) NASA researchers in the US have created a new energy-based benchmark for quantum advantage and have used it to show that noisy intermediate-scale quantum (NISQ) computers use several orders of magnitude less energy than the world’s most powerful supercomputer when doing a specific task.
One sticking point is how to define efficiency, and researchers have usually considered the time taken to solve a problem. In this latest study, Salvatore Mandrà and colleagues at NASA’s Ames Research Center in California, Google and Oak Ridge National lab argue that considering time alone is problematic. Mandrà explains, “A problem that will take you 1 h on a one-core processor will take you 30 min on a two-core processor or 15 min on a four-core processor”.
Instead, Mandrà and colleagues calculated the energy required by both NISQ and conventional supercomputers to solve the RQC problem. They designed a program called qFlex, which they believe to be the most efficient quantum simulator possible. This is demonstrated, explains Mandrà, by the fact that the efficiency of the simulation is almost constant regardless of the details of the problem it is applied to.
“Lots of papers are developing classical algorithms to simulate quantum systems because there’s a lot of quantum systems around and physicists care about how they behave,” says Daniel Gottesman of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, who was not involved in the research. “The specific focus on quantum supremacy is a moment in time that will probably extend for a few years, but after that it will probably be assumed that we have quantum computers that are better than classical computers, and the idea of classical algorithms to simulate quantum computers will become less and less valuable.”