Quantum computers have burst onto the marketplace, with so-called “quantum annealers” being bought up by several big-name companies. Despite the excitement, researchers are not yet certain that quantum annealing can perform faster than conventional computing. Confirming these doubts, new theoretical work shows that quantum annealing faces a fundamental limitation: as machines grow larger, they must be cooled ever closer to absolute zero.
Quantum annealers are designed to work on optimization problems, such as finding the lowest-energy state in a large landscape of candidate states. Unlike traditional computers, there are no logic gates in a quantum annealer. Instead, the qubits in the device are coupled together in a way that mimics the problem to be solved. Through quantum interactions, the qubits evolve toward the optimum configuration. Current state-of-the-art annealers, like those sold by Vancouver-based D-Wave Systems, have solved a number of problems, but so far these tests haven’t shown any significant speed-up over classical machines.
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