Published in the journal Science, Quantum computational advantage using photons by Han-sen Zhang, et al reports a successful demonstration of Quantum Advantage solving a problem of Gaussian Boson Sampling.
Research teams lead by Jian-wei Pan in labs at the University of Science and Technology China in Hefei and Shanghai constructed and programed the Jiŭzhāng Photonic Computer grabbing the crown for quantum supremacy from Google’s Sycamore Computer, which relies on electronic superconductor technology fundamentally slower than the photonic technology employed by Jiŭzhāng.
To put it into perspective in lay terms, Wired states:
LAST YEAR GOOGLE won international acclaim when its prototype quantum computer completed a calculation in minutes that its researchers estimated would have taken a supercomputer 10,000 years. That met the definition for quantum supremacy—the moment a quantum machine does something impractical for a conventional computer.
Thursday, China’s leading quantum research group made its own declaration of quantum supremacy, in the journal Science. A system called Jiuzhang produced results in minutes calculated to take more than 2 billion years of effort by the world’s third-most-powerful supercomputer.
The two systems work differently. Google builds quantum circuits using supercold, superconducting metal, while the team at University of Science and Technology of China, in Hefei, recorded its result by manipulating photons, particles of light.
Putting a finer point on the scale of the computational achievement, Philip Ball, writing in Nature explains that the speed of calculation is unachievable by electronic computing:
They have used beams of laser light to perform a computation which had been mathematically proven to be practically impossible on normal computers. The team achieved within a few minutes what would take half the age of Earth on the best existing supercomputers. Contrary to Google’s first demonstration of a quantum advantage, performed last year, their version is virtually unassailable by any classical computer. The results appeared in Science on 3 December1.
“We have shown that we can use photons, the fundamental unit of light, to demonstrate quantum computational power well beyond the classical counterpart,” says Jian-Wei Pan at the University of Science and Technology of China in Hefei. He adds that the calculation that they carried out — called the boson-sampling problem — is not just a convenient vehicle for demonstrating quantum advantage, but has potential practical applications in graph theory, quantum chemistry and machine learning.
“This is certainly a tour de force experiment, and an important milestone,” says physicist Ian Walmsley at Imperial College London.
As with Google’s Sycamore and various other quantum computing platforms under development by IBM, Amazon and various other commercial and academic institution, the USTC Jiŭzhāng is a purpose built Proof of Concept system rather than a general-purpose computer comparable to those we use to read Daily Kos or play Demon Slayer [sorry, gamers, your over-clocked PCs do not rate].
Quantum technology is still in it’s infancy and would not expect to see much practical use outside of research labs for years, but despite the purpose built nature of the hardware and code, it is conceivable that quantum computers will find practical application to solve complex scientific problems, accelerate certain AI tasks and be used by governments in computer modeling for peaceful or not so peaceful ends, including by intelligence agencies to rapidly defeat current encryption schemes.
This will surely put another log on the fire of the US-China technology race, but readers should understand that science is brainwork and good ideas come from everywhere, so the more important fires this will light will be in human brains around the world.
For the USTC Hefei diagrams released to public domain in Science and links to the open source Diagrams and PowerPoints, see below.
Figure 1 | F1 Powerpoint — Quantum light sources for the GBS
Figure 2 | F2 Powerpoint — Phase-locking from the photon sources to the interferometer
Figure 3 | F3 Powerpoint — Experimental validation of the GBS
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