By Reece Ashton

On October 26, scientists from the University of Science and Technology of China (USTC) unveiled the Zuchongzhi 2.1. Named after a renowned Chinese mathematician and astronomer from the 5th century, the Zuchongzhi 2.1 can reportedly perform large-scale random quantum circuits 10 million times faster than the Fugaku, a Japanese-developed supercomputer that was previously the world’s fastest. The Zuchongzhi 2.1 can also make calculations 1 million times more complex than those made by Google’s Sycamore processor. This breakthrough comes in the wake of China’s recent success with the quantum computer Jiuzhang last year, a prototype capable of detecting up to 76 photons.

The Zuchongzhi 2.1

The USTC research team that developed the Zuchongzhi 2.1 was led by famed quantum physicist Pan Jianwei, who’s also known as the “Father of Quantum” in Chinese quantum circles. Pan’s previous successes include the development of the world’s first quantum satellite, which distributes entangled photons between the ground and the Earth’s satellite orbit.

Consequently, the release of the Zuchongzhi 2.1 was highly anticipated by the community. The resulting supercomputer is claimed to be the fastest programmable 66-qubit superconducting quantum computing system.

These unbelievably fast calculations are facilitated by printed circuit boards constructed according to high-speed design principles. These allow it to switch states so quickly that the transition is complete before the signal finishes traveling between components. Wiring these boards together can also facilitate quantum processing on a larger scale. As a result, the system has an average readout fidelity of 97.4%.

“We estimate that the sampling task finished by Zuchongzhi in about 1.2 hours will take the most powerful supercomputer at least 8 years,” Pan’s team wrote in the journal Physical Letter Reviews on October 25.

What this means for quantum computing

Ultimately, there are two major ways to demonstrate quantum computational advantage: Gaussian boson sampling (GBS) and random quantum circuit sampling based on superconducting qubits. China accomplished the first with the Jiuzhang last December. Pan’s team was even able to improve on its design with the Jiuzhang 2.0, which can detect up to 113 photons and even conduct large-scale GBS a septillion times faster than the world’s fastest supercomputer to date.

“Compared with Jiuzhang, we have greatly improved the performance and collection efficiency of the quantum light source, increased the number of detected photons, and demonstrated the phase-programmability of the GBS quantum computer,” explained USTC researcher Lu Chaoyang.

With the Zuchongzhi 2.1 capable of random quantum circuit sampling at a much faster rate, China is officially the first country to demonstrate quantum computational advantage in two major technical aspects.

“Our research has entered its second stage to start realizing fault-tolerating quantum computing and near-term applications such as quantum machine learning and quantum chemistry,” concludes USTC researcher Zhu Xiaobo.

November 11, 2021