(ZDNet) In what has been hailed as a computing milestone, a team of researchers from the University of Science and Technology of China has achieved quantum supremacy thanks to a device that can manipulate tiny particles of light. Dubbed Jiuzhang, the system performed a quantum computation called “Gaussian boson sampling”, which has been shown to be intractable for classical computers.
While Jiuzhang achieved Gaussian boson sampling in just 200 seconds, the researchers estimated that the same calculation would take the world’s fastest supercomputer, Fugaku, 600 million years to complete. Instead of particles of metal, Jiuzhang manipulates photons. The device was built specifically for the quantum task that it carried out, Gaussian boson sampling, which consists of simulating and predicting the erratic behavior of photons.
The researchers equipped Jiuzhang with 300 beam splitters and 75 mirrors, and said that they managed to measure up to 76 photons during their experiments – enough particles of light to make the calculation intractable for a classical computer.
Christine Silberhorn, professor of integrated quantum optics at Paderborn University in Germany, has been working on Gaussian boson sampling for many years. “The scheme has its own challenges,” she tells ZDNet. “Scaling up the system is hard, because all components have to be engineered for a quantum experiment, and they have to work accurately together. Moreover, it requires the detections and processing of very large datasets.”
Researchers have recently taken interest in photonic quantum computers because of the potential that particles of light have to remain stable even in uncontrolled environments. Unlike devices based on superconducting qubits, photons don’t require extreme refrigeration, and could in theory scale up much faster.
Cracking the Gaussian boson sampling equation has limited usefulness. For now, in fact, the experiment has done little more than show that Jiuzhang is better than classical computers at solving one very specific task – simulating the unpredictable behavior of photons.
“The Boson sampling experiment reported by the USTC group is a real tour de force, and illustrates the potential of photonics as a quantum technology platform,” Ian Walmsley, chair in experimental physics at Imperial College London, told ZDNet. “This is a real step forward in developing technologies that harness the power of quantum physics to perform tasks that that are not possible using current technologies.”

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