A research team including Chinese quantum physicist Pan Jianwei established a quantum computer prototype, named "Jiuzhang," the team announced Dec. 4, 2020.(Xinhua)
HEFEI, Feb. 23 (Xinhua) -- Around a canopy-like freezer hung from the ceiling at a lab in the eastern Chinese city of Hefei, a group of scientists were busy installing one of the most intricate machines humankind had ever invented -- a quantum computer.
Li Shaowei played a major part in this task. The researcher-cum-engineer gingerly took a palm-sized cube out of a box. The 3D-encapsulated device, a quantum processor with 176 qubits, was primed to achieve an overwhelming computational acceleration that is currently not feasible for traditional computers, an ability known as "quantum supremacy."
Instead of mazy transistors, this processor contains minutely printed Josephson junctions, a structure less than a micron in size and featuring a thin layer of aluminium oxide sandwiched between two layers of aluminium.
When the temperature gets close to absolute zero, two aluminium layers will display zero resistance or superconductivity, in a bid to form quantum states that can bolster an exponentially-growing calculating capacity.
But now, the quantum-based circuit wafer was sealed inside a metal case with nearly 200 holes allowing connection with wires dangled down from the freezer above.
Standing on a table, Li took about two hours to complete the connecting work. During the past six years, more than ten superconductivity-driven prototypes were created, among them the prestigious Zuchongzhi 2.1, currently running and making a repetitive "ku-choo" sound at another lab in the building.
Zuchongzhi 2.1 is a 66-qubit programmable quantum computing system made in 2021, which can perform large-scale random quantum circuits sampling about 10 million times faster than the fastest supercomputer at that time.
"Like Zuchongzhi 2.1, the new system has 66 digital qubits plus 110 coupling ones," said Li, who works at the University of Science and Technology of China (USTC). "I have to link each qubit with its corresponding wire, otherwise they may lose control," Li added.
The team then managed to package the quantum system variable-sized, Matryoshka doll-like vacuum jars and used liquid helium to help realize an absolute zero working environment.
The prototype computer in a cylinder shape reminded Xu Yu, a post-doctoral researcher, of Zordon of Eltar, the protagonist in the U.S. superhero television series Power Rangers, who has only a brain soaked in a jar.
Xu said the system under assembly, a replicate of Zuchongzhi 2.1, was projected to be linked to a cloud platform for quantum computing, making it accessible to other research institutions and even the public.
In 2019, Google reported the existence of a 53-qubit superconducting processor called Sycamore that performed the quantum random sampling task in 200 seconds, and the designers said then that it would take the world's fastest supercomputer 10,000 years to produce a similar output.
The 66-qubits Zuchongzhi 2.1 is one million times faster than the speed Sycamore could produce back in 2019. "Superconducting computing is a technical route believed to be the best strategy for developing quantum computing to a stage where it can be used for tasks similar to those performed by a general-purpose computer," Xu added.
Another group of scientists from the USTC also created a quantum computer prototype, named "Jiuzhang," with a photon-driven strategy. Jiuzhang 2.0 was shown in 2021 to have implemented Gaussian boson sampling, a classical simulation algorithm, with 113 detected photons, which was septillion times faster than the world's fastest existing supercomputer.
These two technical routes have placed China at the forefront of developing and commercializing quantum computing, driving the country to become one of the global leaders in this sector.
China is also home to a number of startups working on quantum technology such as Origin Quantum, a Hefei-based unicorn company that launched OriginQ Cloud, a full-stack quantum computing cloud service platform.
Currently, quantum computers excel in certain less-practical tasks like quantum random sampling and Gaussian boson sampling. In the near future, more practical quantum computers are expected to push artificial intelligence to new heights, and design entirely new materials, chemicals, and medicines.
Having achieved quantum supremacy, scientists in the global quantum computing race are now placing more emphasis on improving the machine's performance by focusing on error-correcting and the qubit's operating life.
"With ever-known algorithms, the high-quality automatic error correction for a quantum computing prototype may require thousands of qubits," said Xu. "Also, efforts are still needed to prolong the duration of quantum states so that the qubits can be utilized to calculate as long as possible."
To achieve such goals, much more manpower is needed to participate in quantum research, and that's the reason they work hard to connect new systems to a cloud platform, said Xu.
The public can log the platform for free and attempt to create quantum computing programs to help figure out more algorithms, according to Xu.
"Just play around on it. Who knows when a genius may work out an excellent algorithm that advances quantum tech and heralds the second information revolution," said Xu.
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