This breakthrough made my country the second country in the world to achieve “quantum superiority”.

On December 4, the University of Science and Technology of China announced that a research team composed of Pan Jianwei and Lu Chaoyang of the University of Science and Technology of China, in cooperation with the Shanghai Institute of Microsystems of the Chinese Academy of Sciences, and the National Parallel Computer Engineering Technology Research Center, has constructed 76 photon quantum computing prototypes. “Nine Chapters”.

The name “Nine Chapters” is to commemorate the earliest mathematics monograph “Nine Chapters Arithmetic” in ancient China.

Realize the superiority of my country’s first quantum computing and crush Google’s “quantum hegemony”

Quantum superiority, the “quantum hegemony” that Google claims here, is a direction that has attracted much attention in quantum computing in recent years. The success of the “Nine Chapters” has enabled my country to successfully reach the first milestone in quantum computing research!

Quantum computing refers to the use of the principle of quantum coherent superposition, which can solve some problems beyond traditional computers, and has ultra-fast parallel computing and simulation capabilities.

The optical quantum computer consists of 3 main parts:

The first part is a single-photon source. At a low temperature of minus 269 degrees Celsius, this device excites quantum dots with lasers to produce a high-quality single photon each time.

The second part is the ultra-low loss optical quantum circuit. The single photon is divided into 5 paths through the switch, and is led into the optical quantum network of the main device through the optical fiber.

The third part is the single-photon detector, which detects the quantum calculation results obtained in the matrix.

The experiments of Pan Jianwei’s team used photons to achieve quantum computing, and most of the experiments were carried out at room temperature.

Figure | “Nine Chapters” Quantum Computing Prototype Optical System Schematic Diagram

They divided a customized laser beam into 13 paths of equal intensity, focused on 25 crystals to produce 25 quantum light sources with special states. Above), enter the interferometer and “talk” with each other, the final output result is detected by 100 superconducting nanowire single-photon detectors, and finally 76 detectors detected photons.

“Gaussian Bose sampling” is a complex sampling calculation. When the problem scale exceeds a certain value, any traditional computer cannot effectively simulate it, and Bose sampling is one of these specific problems. However, the single-photon source required for Bose sampling is difficult to implement on a large scale in experiments. Therefore, people consider a variant of the problem-Gaussian Bose, a more efficient method of calculating sampling probability, which greatly reduces the amount of analog sampling required. cost.

According to the current best classic algorithm, “Nine Chapters” is 100 trillion times faster in processing Gaussian Bose sampling than the world’s number one supercomputer “Fuyue”, which is equivalent to the 53-bit quantum computing prototype released by Google last year. The machine “Platanus” is ten billion times faster.

At the same time, the superiority of quantum computing proved by Gaussian Bose sampling does not depend on the number of samples, which overcomes the loophole that the quantum superiority depends on the number of samples in Google’s 53-bit random line sampling experiment. The output quantum state space scale of “Nine Chapters” has reached 1030 (the output quantum state space scale of “Platanus” is 1016, and the current world storage capacity is 1022).

Barry Sanders, Professor of the University of Calgary and Director of the Institute of Quantum Science and Technology, said:

I think this is an outstanding work that has changed the current landscape (It’s the game changer). We have been working hard to prove that quantum information processing can defeat classical information processing. This experiment makes the classic computer unmatched.

Last year, Google achieved a huge result, that is, the superiority of quantum computing, but this is controversial…This experiment (the experiment of Academician Pan Jianwei’s team) is not controversial, and there is no doubt that the results of the experiment far exceed The simulation capabilities of traditional machines are improved.

In addition, the Gaussian Bose sampling algorithm based on the “Nine Chapters” quantum computing prototype has potential applications in graph theory, machine learning, quantum chemistry and other fields, and will be an important direction for subsequent development.

The team behind “Nine Chapters”: Quantum superiority experiments are not accomplished overnight

In terms of optical quantum information processing, Pan Jianwei’s team has always been at the international leading level.

In 2017, the team built the world’s first optical quantum computing prototype that surpassed the early classical computer (ENIAC).

In 2019, the team further developed the world’s highest performance single-photon source with deterministic polarization, high purity, high identity and high efficiency, and realized the Bose sampling of 20-photon input and 60-mode interference circuit, and the output complexity is equivalent to 48 quantum The Hilbert state space of bits approaches the “superiority of quantum computing”.

The results of this time have further firmly established my country’s position as the first square matrix in international quantum computing research, and laid the technical foundation for the realization of large-scale quantum simulators that can solve problems of great practical value in the future.

Nowadays, every country hopes to compete for the commanding heights of science and technology, and the application of quantum science to science and technology is likely to be the key to victory.

It is worth noting that related papers were published online in the internationally renowned academic journal Science in the early morning of December 3.

The reviewers of “Science” evaluated the work as “a most advanced experiment” and “a major achievement.” In addition, there are many experts from the American Academy of Sciences, well-known universities, and research institutions who have spoken highly of the latest achievements in the field of quantum science.

For this study, participant Lu Chaoyang expressed in an interview that he hopes that this work can inspire more work in classical algorithm simulation, and it is also expected that there will be room for improvement in the future. Quantum superiority experiment is not a one-time task, but a competition between faster classical algorithms and ever-increasing quantum computing hardware, but in the end, quantum parallelism will produce computing power that classical computers cannot match.

The Links: **LQ084S3LG02** **LQ150X1LGN2**