The new light-based quantum computer Jiuzhang has achieved quantum supremacy
+ A photonic quantum computer, which harnesses particles of light, or photons, performed a calculation that’s impossible for a conventional computer, researchers in China report online December 3 in Science. That milestone, known as quantum supremacy, has been met only once before, in 2019 by Google’s quantum computer (SN: 10/23/19). Google’s computer, however, is based on superconducting materials, not photons.
Named Jiuzhang after an ancient Chinese mathematical text, the new quantum computer can perform a calculation in 200 seconds that would take more than half a billion years on the world’s fastest non-quantum, or classical, computer.
+ While Google was the first to break the quantum supremacy barrier, the milestone is “not a single-shot achievement,” says study coauthor and quantum physicist Chao-Yang Lu of the University of Science and Technology of China in Hefei. “It’s a continuous competition between constantly improved quantum hardware and constantly improved classical simulation.” After Google’s quantum supremacy claim, for example, IBM proposed a type of calculation that might allow a supercomputer to perform the task Google’s computer completed, at least theoretically.
The quantum computer Jiuzhang works by sending particles of light into a network of channels and then measuring the photons at the other end.
+ One limitation of Jiuzhang, Weedbrook notes, is that it can perform only a single type of task, namely, boson sampling. In contrast, Google’s quantum computer could be programmed to execute a variety of algorithms. But other types of photonic quantum computers, including Xanadu’s, are programmable.
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