Quantum computing has been one of those long-promised breakthroughs, forever on the horizon yet just out of reach, but a quickening is upon us with Google, IBM and others vying to cross a major threshold in a matter of months (as reported recently by MIT News). The target they are gunning for is quantum supremacy, the term coined by theoretical physicist John Preskill to define the point at which a quantum processor surpasses the ability of the largest classical supercomputer to carry out a well-defined problem.
A front-runner in the global supercomputing race, China is also proving itself as a world leader in quantum research. At a press conference in Shanghai on Wednesday, a quantum research team from Eastern China announced they had a hit a milestone in creating a quantum machine that can compete with today’s classical computers.
Team leader quantum physicist Pan Jianwei, an academician of the Chinese Academy of Sciences and his colleagues Lu Chaoyang and Zhu Xiaobo (of the University of Science and Technology of China), and Wang Haohua (of Zhejiang University) reported that their quantum processors could solve certain tasks faster than classical machines.
The researchers’ quantum device is called a boson sampling machine, considered “a strong candidate to demonstrate ‘quantum computational supremacy’ over classical computers,” according to the team. At the crux of the advance are two primary components: “robust multiphoton interferometers with 99% transmission rate and actively demultiplexed single-photon sources based on a quantum dot–micropillar with simultaneously high efficiency, purity and indistinguishability.”
The scientists’ implementations of three-, four- and five-photon boson sampling achieve sampling rates of 4.96 kHz, 151 Hz and 4 Hz, respectively, reaching speeds 24,000 times faster than previous experiments. “Our architecture can be scaled up for a larger number of photons and with higher sampling rates to compete with classical computers,” they write in their paper, which was published in the scientific journal Nature Photonics on Tuesday.
The Chinese team said their prototype quantum computing machine is 10 to 100 times faster than the first electronic computer, ENIAC, and the first transistor computer, TRADIC, and could “one day could outperform conventional computers.”
University of Texas at Austin Professor Scott Aaronson, who proposed the boson sampling machine, reported that the research showed “exciting experimental progress.”
“It’s a step towards boson sampling with say 30 photons or some number that’s large enough that no one will have to squint or argue about whether a quantum advantage has been attained,” he told the South China Morning Post.
Pan Jianwei is also the chief engineer of the world’s first quantum satellite, launched by China in August 2016. The goal of the project is to secure ultra-secure “hack-proof” quantum communications and to demonstrate features of quantum theories, such as entanglement. In January, Jianwei stated, “the overall performance has been much better than we expected; it will allow us to conduct all our planned experiments using the satellite ahead of schedule and even add some extra ones.”