Earlier this year, researchers at the Flatiron Institute’s Center for Computational Quantum Physics (CCQ) announced that they had successfully used a classical computer and sophisticated mathematical models to thoroughly outperform a quantum computer on a task that some thought only quantum computers could solve. Now, those researchers have determined why they were able to trounce the quantum computer at its own game. Their answer, presented in Physical Review Letters, reveals that the quantum problem they tackled—involving a particular two-dimensional quantum system of flipping magnets—displays a behavior known as confinement. This behavior had previously been seen in quantum condensed matter physics only in one-dimensional systems. This unexpected finding is helping scientists better understand the line dividing the abilities of quantum and classical computers and provides a framework for testing new quantum simulations, says lead author Joseph Tindall, a research fellow at the CCQ. “There is some boundary that separates what can be done with quantum computing and what can be done with classical computers,” he says. “At the moment, that boundary is incredibly blurry. I think our work helps clarify that boundary a bit more.” By harnessing principles from quantum mechanics, quantum computers promise huge advantages in processing power and speed over classical computers. While classical computations are limited by the binary operations of ones and zeros, quantum computers can use qubits, which can represent both 0 and 1 simultaneously, to process information in a fundamentally different way.

Full report : How a classical computer beat a quantum computer at its own game.