Chinese scientists unveiled a quantum computer prototype named "Jiuzhang 3.0" with 255 detected photons on Wednesday, once again pushing the boundaries of photonics quantum computing technology.
Led by the renowned Chinese quantum physicist Pan Jianwei, the research team has successfully accomplished this quantum computing feat, achieving a speed that is 10 quadrillion times faster in solving Gaussian boson sampling (GBS) problems compared to the world's existing fastest supercomputers.
Gaussian boson sampling, a classically intractable problem, was employed in this study to provide a highly efficient way of demonstrating quantum computational speedup in solving some well-defined tasks.
The study was published online in the journal Physical Review Letters on Wednesday Beijing Time.
Quantum computing is a groundbreaking mode of computation, calculating by orchestrating quantum bits in adherence to the principles of quantum mechanics. Nobel Laureate Richard Feynman first put forward the concept of quantum computers in 1981.
China's photonics quantum computer prototype, named "Jiuzhang," after the ancient Chinese mathematical masterpiece "Nine Chapters on the Mathematical Art," was built in December 2020, achieving quantum computational advantage with up to 76 detected photons.
"Jiuzhang" made China the second country in the world to achieve quantum computational advantage, also known as "quantum supremacy," indicating an overwhelming quantum computational acceleration that is currently not feasible for traditional computers.
Lu Chaoyang, a member of the research team and professor at the University of Science and Technology of China, said that a series of innovations, including a newly developed superconducting nanowire single-photon detection scheme with fiber loop-based configuration, increased the number of detected photons for "Jiuzhang 3.0" to 255, greatly improving the complexity of photonics quantum computing.
"By demultiplexing photons into time bins through delays, we've achieved capabilities of pseudo photon number resolving," Lu added.
According to the state-of-the-art exact classical simulation algorithm, "Jiuzhang 3.0" is a million times faster at solving GBS problems than its predecessor, "Jiuzhang 2.0." Moreover, the most complex samples of GBS that "Jiuzhang 3.0" can calculate in just one microsecond would take the world's fastest supercomputer, "Frontier," more than 20 billion years to complete.
Lu pointed out that, despite many upgrades and innovative achievements, "Jiuzhang 3.0" is still a long way from becoming a universal quantum computer.
"Universal quantum computers might require the manipulation of tens of millions of qubits and error correction capabilities. These are among the future challenges. The practical application of quantum computing is an ongoing relay race," Lu said.
In 2021, the team led by Pan developed the "Jiuzhang 2.0" with 113 detected photons and a 66-qubit programmable superconducting quantum computing system named "Zuchongzhi 2.1," making China the only country to achieve a quantum computational advantage in two mainstream technical routes -- one via photonics quantum computing technology and the other via superconducting quantum computing technology.
The global landscape for quantum computing is on an accelerated trajectory, where countries and tech behemoths, including IBM and Google, are engaged in a spirited race. Governments and related industries are also doubling down on research investments and policy support for quantum computing.
Highlighting the extraordinary parallel computing capability of quantum computers, Pan stated that quantum computing is poised, through specific algorithms, to offer enhanced computational power compared to traditional computers, especially in realms like cryptography, big data optimization, weather forecasting, material design and drug analysis.
The team noted that establishing quantum computational advantage requires great endeavor, with long-term competition between classical algorithms and quantum computing hardware.
They anticipate that this work will, on the one hand, stimulate more research on classical simulation algorithms, and on the other hand, through diligent efforts, gradually address various scientific and engineering challenges in quantum computing research. Ultimately, quantum computers will achieve computational power beyond the reach of classical computers, driving the advancement of science and technology.