2 months and 7 top issues! Guangcan Guo's team achieves the fastest international regulation of silicon spin quantum bits
With its long quantum decoherence time and high manipulation fidelity, as well as its high scalability compatible with modern semiconductor process technologies, the silicon-based semiconductor spin quantum bit is one of the important candidates to realize the development of quantum computers. In recent years, substantial progress has been made in silicon quantum dot-based research due to their superiority.
High manipulation fidelity requires bits to have faster manipulation rates while having long quantum decoherence times. Conventional schemes use electron spin resonance to achieve spin bit flipping, which has a slow bit manipulation rate. The researchers found that using the electric dipole spin resonance mechanism to achieve spin bit flip has a faster manipulation rate; at the same time, the manipulation rate of bits is positively correlated with the strength of spin-orbit coupling in the system, and in order to obtain higher gate fidelity in applications such as quantum error correction, it is desirable to further optimize the speed of electric dipole spin resonance (EDSR) to achieve fast electrical manipulation of hole spins.
Therefore, effective regulation of the strength of the spin-orbit coupling in the system is an important physical basis for achieving high-fidelity manipulation of spin-quantum bits.
In this time, Prof. Guo Guoping and Prof. Li Haiou from academician Guo Guangchan's team, in collaboration with Assistant Researcher Huang Peihao from SUSTech Institute of Molecular Science and Engineering, Researcher Zhang Jianjun from Institute of Physics, Chinese Academy of Sciences, and Hongyuan Quantum Computing Co., Ltd. have achieved the electric field regulation of spin quantum bit manipulation rate in silicon-based germanium quantum dots, and the ultra-fast manipulation of spin quantum bits with spin flip rate over 1.2 GHz.
On April 26, the research results were published online in the International Journal of Nanodevice Physics as "Ultrafast and Electrically Tunable Rabi Frequency in a Germanium Hut Wire Hole Spin Qubit". The research results were published online in Nano Letters, a leading international journal on the physics of nanodevices.
This rate is the highest reported in the international semiconductor quantum dot system, and this work is also an important guide to enhance the quality of spin quantum bits.
In order to further enhance the performance of spin quantum bits, the experimental team found that the electric field parameters (quantum dot detuning and gate voltage) in the system have a significant modulation effect on the manipulation rate of spin quantum bits. Through physical modeling and data analysis, the researchers have self-consistently explained the experimental results of electric field modulation on the manipulation rate of spin quantum bits by using the modulation effect of electric field strength on the spin-orbit coupling effect in the system and the contribution of the orbital excited states in the quantum dots to the manipulation rate of the bits.
The experimental results have further measured the ultra-fast spin bit manipulation rate of more than 1.2 GHz, which is the fastest record of 540 MHz for semiconductor spin bit manipulation rate previously set by the group [NatureCommunications13, 206 (2022)].
Experimental setup and cavity spin quantum bits
Manipulation of ultrafast hole spin quantum bits with a maximum Rabi oscillation frequency of more than 1.2 GHz.
Finally, the team stated, "Our work paves the way for the study of scalable spin quantum bits."
It is worth mentioning that since March 2023, this is the seventh academic paper published by Academician Guangcan Guo's team in the top journal (refer to the CAS division): since early April, the team has published articles in Nature Communications, Nature Physics, Nature Materials, and other journals, covering quantum networks, quantum computing, quantum precision measurement, fundamental research, and other technological breakthroughs.
The octogenarian academician, it seems, is leading the team to pioneer a full range of quantum scientific research.
Inside the Key Laboratory of Quantum Information of the Chinese Academy of Sciences at the University of Science and Technology of China, Guo Guangcan's office is filled with young people coming in and out every day. "Young people come to me to discuss topics, report progress, discuss countermeasures, and even have a chat." Guo Guangcan says he basically comes to the office every day as long as he doesn't leave Hefei - despite being more than 80 years old.
Guo Guangcan, the pioneer, forerunner and founder of quantum optics and quantum information science in China. He is a member of the Chinese Academy of Sciences, a member of the Third World Academy of Sciences, a professor at the University of Science and Technology of China, and former chairman of the Optical Society of China. Image source: Xinhua
Since the 1980s, Guo Guangcan has taken the lead in carrying the banner of quantum research in China, "opening up" and "plowing" the land where the development of quantum optics and quantum informatics is still barren.
In the 1970s, Guo Guangcan successfully developed China's earliest nitrogen molecular laser, which was awarded the National Science Congress Award. 1981-1983, Guo Guangcan was sent to Canada to visit and study. It was at the University of Toronto that he discovered that the international academic community had been conducting research in quantum optics for more than 20 years.
After returning to China, Guo Guangcan began to plan and implement the promotion of quantum optics, and China's quantum optics research finally began to stumble, laying the foundation for China's later achievements in quantum information technology in many world leaders.
In the 1990s, Guo Guangcan, who was in his fifties, gradually came across a new word: quantum information, and with his keen academic sense, he sensed that this could be a breakthrough in quantum optics. But he didn't even know what "classical information" was. So he sought advice from a professor at the School of Information Science and Technology of the Chinese University of Science and Technology, and started to learn coding from "0101".
Guo Guangcan drafts materials in his office, which is full of documents and books. Photo credit: Xinhua
Guo Guangcan's team was the first to carry out research in the field of quantum information, and the first to achieve results, completing the first major work in the field, quantum coding, in 1997. For the first time, he proposed the "decoherence-free subspace", i.e. a special quantum state that would not be decoherent, and only decoherent quanta would be encoded onto this special quantum state when needed to avoid errors.
The paper on quantum error avoidance coding by Kuo's team was published in Physical Review Letters, which caused a sensation in the quantum information community at home and abroad, and the method was later confirmed experimentally by several famous laboratories in the United States. In this year, Guo Guangcan's research work shifted from theory to experiment, and he started to apply for "973" projects since 1997.
In 1998, Guo Guangcan organized the Quantum Information Xiangshan Scientific Conference, he wrote to Qian Xuesen, proposing that he should promote the development of quantum information in the spirit of "two bombs and one star" to seize the first opportunity, and invited Qian to be the chairman of the Xiangshan Conference. Qian Lao was then in old age and physical decline, but still wrote back to express his affirmation: "What you say is very important, I support you very much."
In 2000, Guo Guangcan's team made a sensation in the world again with their research on "the preparation of two-atom entanglement scheme using optical cavities". French scientist Serge Haroche later proved the theory experimentally and won the Nobel Prize in Physics in 2012.
Guo Guangcan was too happy to achieve significant results, because his application for the "973" project was repeatedly unsuccessful. But Guo Guangcan did not intend to give up, he thought that the "973" target is "national major needs of basic research", and the quantum information, quantum cryptography application prospect is attractive, should be funded. However, at that time, the entire academic community lacked understanding of this field and did not think highly of Guo Guangcan's research.
But in 2001, things turned around, and the 2001 International Symposium on Quantum Information was held in Huangshan, Anhui Province, China, the first international conference on quantum information held in China, attracting many international experts, including Professor Bennett of IBM (who proposed the BB84 protocol), Professor Zoller of Austria (who first proposed the paper on ion-well quantum computers), Prof. Grover of Bell Labs (who proposed the Grover algorithm), and Prof. Songhao Liu, a member of the Chinese Academy of Sciences, among others.
During this conference, Guangcan Guo became a household name in the science and technology community. He gave the opening speech as the academic leader of China's research in the field of quantum information and as the executive chairman of the conference. Finally, in 2001, the fourth year of Guo Guangcan's repeated failures, China's first "973" project on quantum communication and quantum information technology was approved.
In the subsequent evaluation of Chinese Academy of Sciences laboratories, Guo Guangcan's team's quantum information laboratory ranked first and was exceptionally upgraded to a key laboratory of Chinese Academy of Sciences. Guo Guangcan in the "973" project as the chief scientist, and gathered more than 50 researchers from more than a dozen domestic research institutes and universities to participate in the project, and even later out of five CAS academicians: in addition to Guo Guangcan, and Pan Jianwei, Du Jiangfeng, Peng Kuanchi, Sun Changpu.
In 2003, at the age of 61, Guo Guangcan was elected to the Chinese Academy of Sciences and won the second prize of the National Natural Science Award and the He Liang He Li Award.
In 2008, Guo Guangcan's team proved for the first time the non-additivity of the private capacity of the quantum channel, solving a problem that had been pending for more than 10 years and completing the "trilogy" of the non-additivity of the three capacities of the quantum channel.
In 2009, Guo Guangcan's team built the world's first "quantum government network" in Wuhu City, which is an important symbol of the beginning of industrialization of China's quantum confidential communication basic research results.
In 2016, Guo Guangcan's team set up a joint research institute with Hengtong Optoelectronics and completed the first WAN project - "Ning-Su Quantum Backbone" in 2017, which is also the world's first phase-coded long-distance commercial quantum backbone.
In 2017, the first domestic quantum encrypted cell phone, jointly developed by Ask Quantum and China Academy of Space Systems Science and Engineering, was officially released. Guo Guangcan also started a second business, relying on the Chinese Academy of Sciences Key Laboratory of Quantum Information, Guo Guangcan and Guo Guoping jointly established the first quantum computing company in China - Origin Quantum, focusing on quantum computing full stack development, various software and hardware products with leading technical indicators in China, and has applied for more than 100 patents.
Guo Guangcan, who is already 80 years old, is still working tirelessly at his job, contributing to the development of quantum information science. The picture shows the academician in the solid-state quantum storage laboratory.
Academician Guo Guangcan dives into his research in the ultra-clean laboratory for quantum chip processing and testing. Photo source: Xinhua
Semiconductor quantum chip is one of the key directions of Guo Guangcan's team's future research.
In 2021, Guo Guangcan won the second prize of the 2020 National Natural Science Award for his "Research on fundamental problems of quantum physics based on quantum information technology".
At the end of 2022, Guo Guangcan published an article in the People's Daily, "Quantum computing - powerful arithmetic power, broad prospects", saying, "I look forward to the continuous use of China to improve the performance of the quantum special machine. We expect China to improve the performance of quantum-specific machines in continuous use and form a good development ecology of 'development-use'. This requires us to accurately analyze the R&D and application prospects of quantum computing software and hardware technologies, scientifically and rationally formulate the overall development strategy, clarify the near-term, medium- and long-term goals, and invest and assess in phases to promote better and faster development of quantum computers and help China's socialist modernization."
Exploration will continue, Guo Guangcan firmly believe that the quantum computer will be able to get out of the laboratory, start engineering construction, and eventually move towards industrialization and be used by all the people of the country.
Reference links:
[1]https://news.ustc.edu.cn/info/1055/82885.htm
[2]https://pubs.acs.org/doi/10.1021/acs.nanolett.3c00213
[3]https://www.thepaper.cn/newsDetail_forward_21514729
[4]http://www.news.cn/2022-06/15/c_1128740648.htm
[5]https://mp.weixin.qq.com/s/ss_I-KlQfrnYrQnM6iUuMg
