The field of quantum computers continues to develop in its infancy stage, but that development is beginning to move at a much faster rate. China has just published a paper in the journal Science, in which they describe Jiuzhang, their photonic quantum computer, that demonstrated quantum supremacy.
Quantum supremacy happens the moment a quantum machine does something which is impractical to a conventional computer, outperforming it on at least one task. Scientists have seen this only one time in the past, with Google’s Sycamore device being the only computer ever to achieve this feat. We can now count China’s Jiuzhang as the second. Jiuzhang has produced results in minutes when it would have taken the world’s fastest supercomputer nearly 2.5 billion years to carry out the same calculation. Google’s Quantum Computer was only able to compute something that would have taken a normal computer 10,000 years. China’s is that much faster.
China’s new Quantum Computer is so fast that some think it might be fast enough to create a simulated reality. If you’re not familiar with Simulation Theory, take a deep dive here. In essence though, Simulation Theory is the idea that if technology progresses long enough at some point humanity will have the ability to simulate an artificial reality with a computer. At that moment, they’ll also create thousands, maybe even millions of artificial simulated realities. And if that happens, then the odds that we ourselves are actually living in an artificial simulated reality are much higher than the odds of us living in the real reality, since there are millions of simulated ones and only one that’s totally real.
We don’t have the software to make a simulated reality happen, but a computer like China’s may be exactly the thing we need to create a simulated world. Simulation Theory suddenly looks more plausible than ever.
When comparing the two quantum computers developed by China and Google, they took different avenues to reach quantum supremacy. While Google’s Sycamore team built its quantum circuits using supercold, superconducting metal, China’s Jiuzhang team from the University of Science and Technology of China got their results by manipulating photons.
The team from China developed their photon-based quantum computer with the capability of carrying out just one specific type of calculation called boson sampling which is used to calculate the output of a multiple-input and output straight-line optical circuit.
While both Jiuzhang and Sycamore used statistical tests to stake their claim of quantum supremacy, they went about it from two completely different directions. Sycamore used what’s known as qubits, or quantum bit, which is the basic unit of quantum information. When used in large numbers, combined qubits will be able to produce quantum computers that can accomplish useful work. The Sycamore was only able to use 53 qubits. Experts estimate that it would take anywhere from hundreds to millions of qubits to have a fully functional quantum computer.
Juizhang used photons to achieve quantum supremacy. These photons traveled through optical circuits that were set on a lab bench and guided by mirrors. When comparing to Sycamore and its qubits, each photon that is read out at the end of the process can be thought of as reading out a qubit.
There is also another significant difference when comparing qubits to photons when it comes to quantum computers. Photonic quantum computing is not easily reprogrammable in efforts to run different calculations. Juizhang could effectively only run one calculation. Even with their limited ability to handle more calculations at the present time, Christian Weedbrook, CEO and founder of Toronto quantum computing startup Xanadu, feels that coming at it from different directions is a good thing. “It’s a milestone in photonic quantum computing,” he said via Wired, “but also good for all of us.”
Though still early in the game, developers such as IBM, Microsoft, Intel, and Amazon, as well as several other large startups, are going all-in on developing quantum computing hardware. The Chinese team has benefited greatly because of the Chinese government’s willingness to be more prominent when it comes to developing quantum technology. But as things develop further, one side feels they may have an advantage. Proponents of the photon approach say eventually their way of cracking the quantum nut is more attractive since they don’t have to build their devices inside ultracold refrigerators. But as Weedbrook summed it up, “We all have pros and cons.”