Computer developed in China achieves 'quantum supremacy'

Computer developed in China achieves 'quantum supremacy'
A new photon-based computer called Jiuzhang, using light to move and store quantum bits, has achieved "quantum supremacy," researchers say. Photo by TheDigitalArtist/Pixabay

Dec. 4 (UPI) -- A new type of quantum computer, developed by a team of scientists from several Chinese research institutions, has achieved "quantum supremacy."

Quantum supremacy is achieved when a quantum computer can best the performance of a supercomputer at just one task.


"Quantum computational advantage is like a threshold," Lu Chaoyang, professor of the University of Science and Technology of China, told China's state news agency Xinhua.

"It means that, when a new quantum computer prototype's capacity surpasses that of the strongest traditional computer in handling a particular task, it proves that it will possibly make breakthroughs in multiple other areas," Chaoyang said.

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Last year, Google's quantum computer became the first to achieve quantum supremacy, performing calculations in a matter of minutes that scientists estimated would take a supercomputer 10,000 years to complete.

Unlike Google's Sycamore computer, which used superconducting materials to manage qubits -- bits of quantum information -- the new Chinese computer, called Jiuzhang, is photon-based, using light to move and store quantum bits.

To prove the computer's quantum supremacy, researchers used it to carry out a type of calculation called boson sampling. The researchers described their success in a new paper published this week in the journal Science.

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Gaussian boson sampling is a classical simulation algorithm that's difficult for classical computers to perform. Boson sampling calculates the distribution of outputs from a straight-line optical circuit featuring multiple inputs and outputs.

Jiuzhang was able to perform the calculations by sending photons through a series of optical circuits guided by mirrors. Moving through the circuits, the photons encounter beam splitters, sending photons simultaneously down different paths.

During their repeated trips through the circuitry, photons are split and merged -- interfering with one another as dictated by quantum mechanics.

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The photons spit out the other the end of the circuits provide a quantum calculation -- qubits that translate to the distribution of outputs.

Jiuzhang completed the boson sampling calculations in just a few minutes. Scientists estimated the same calculations would take some of the world's fastest supercomputers more than half-a-billion years.

The researchers responsible for Jiuzhang's design claim the quantum computer could be adapted to perform calculations useful to graph theory, machine learning and quantum chemistry.

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Similarly, computer engineers with Google have claimed Sycamore can be reprogrammed to perform a variety of calculations.

But so far, quantum supremacy has been achieved using esoteric calculations chosen not because they're particularly useful, but because they're quite hard for classic computers to perform.


Still, the latest news suggests quantum computers, including both those using superconductor and those relying on photons, are closer to offering applicable supremacy.

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"The fact that now the two different platforms are able to achieve this regime ... shows that the whole field is advancing in a very mature way," quantum physicist Fabio Sciarrino of Sapienza University of Rome told Science News.

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