A photonic quantum computer in China shows its ‘supremacy’ over supercomputers

Computers are pretty darn speedy these days. But there’s a limit to what they can achieve in terms of complex calculations in a very short space of time — or even 2.5 billion years. But researchers from several institutions in China are now claiming they have used a new quantum computing demonstration to carried out in just 200 seconds what a classical supercomputer would take this lengthy (to put it mildly) period of time to calculate.

This, the researchers say, is a clear example of what is referred to as quantum supremacy: A task that a programmable quantum device is able to solve that a classical computer would not be able to solve in a feasible period of time.

Just as impressively, it does this with a complex quantum setup involving a light- and mirror-based photonic quantum system of the kind Massachusetts Institute of Technology theoretical computer scientists Scott Aaronson and Aleksandr Arkhipov came up with a decade ago, called a boson sampling machine. Boson sampling involves the computing of a complex optical circuit output. It bounces photons using mirrors, splits light with beam splitters, and more. This particular Chinese demonstration involved 50 photons, 100 inputs and outputs, 75 mirrors, and 300 beam splitters.

China quantum computer
Chao-Yang Lu

If that sounds like a lot of variables to keep track of, you’d be absolutely right. In fact, all current proofs on the difficulty of simulating boson sampling on a classical computer suggest that it is virtually impossible. Calculating the distribution of such a system for Gaussian boson sampling is an extremely hard job because it involves exponentially more steps as the size grows.

“It is the second time in all physical systems, just after Google, and the first time with photons, that showed a quantum computational advantage,” Chao-Yang Lu, a quantum physicist at the University of Science and Technology of China in Hefei, told Digital Trends. “[It shows] the potential of a future quantum computer that is based on the principle of quantum mechanics.”

To be clear, while this is an exciting advance when it comes to showing off quantum mechanics in action, it’s still far from an example of the kind of super-powered quantum computer — which operates fundamentally differently from classical computers — that will revolutionize computing as we know it. Nonetheless, it’s a fascinating proof of concept.

Chao-Yang said that possible opportunities for similar complex problems that could be solved in the quantum space include quantum chemistry and more sophisticated machine learning. “It is still at the very beginning,” said Chao-Yang. “The community is still exploring what kind of problems are suitable for quantum computers.”

A paper describing the work was recently published in the journal Science.

Editors' Recommendations