Two out, two in! Yan Ning returned to this thing, quantum science community also has such a ......

 

One day in July 2010, a phone rang urgently outside the Quantum Information Laboratory at the University of Michigan.

 

The person who made the call, Yao Qizhi, is the only Chinese computer scientist who won the Turing Award, and he and Duan Luming have the same work experience in the United States, and as long as 36 years.

 

In 2001, Duan and his co-workers proposed the famous DLCZ (Duan-Lukin-Cirac-Zoller) quantum relay scheme (Nature, 2001), which uses a combination of atomic quantum memory and single-photon channels to overcome the exponential fading of optical quantum signals in optical fibers, and has since continued to be a research hotspot in this field. This has continued to be a hot topic of research in this field.

 

The moment he received the call, Lu-Ming Duan had an answer in his mind, "I'm willing to go back." He then submitted his resignation to the University of Michigan. After several twists and turns, in 2011, Lu-Ming Duan joined the Quantum Information Research Center at Tsinghua University's Institute for Cross-Information Research, becoming the first Yao Chi-Chi Chair Professor at Tsinghua University, and in 2018, Lu-Ming Duan gave up his tenure at the University of Michigan to return to the Institute for Cross-Information Research full-time, and was appointed the first Tsinghua University Chair Professor of Basic Sciences.

 

After his return, Luming Duan opened up a whole new dimension for quantum science research at Tsinghua University. Now, Tsinghua University is a leading base for quantum science research and education in China.

 

Professor of Basic Science, Yao Qizhi Chair Professor and Doctoral Supervisor, Tsinghua University

Lu-Ming Duan

 

01A "genius" from a humble family

 

In 1972, Duan Luming was born in Tongcheng, Anhui Province, to a family that was not well-off. Until he went to school, he was like other children in the village, playful and not gifted in any way. Later, when he came to school, although his family was not rich, his parents kept saving money for Duan Luming to go to school. He was always curious about all the new things, even a butterfly flying outside the window could draw his attention away, and his mind was not fully focused on his studies. But what was puzzling to his classmates was that he was always at the top of every test, and he knew many things in advance before the teacher talked about them. Gradually, the teacher discovered his talent and focused on Duan Luming.

 

When he went to middle school, there were two additional courses in physics and chemistry, which many middle school students found very difficult to learn, but Duan Luming found these two courses very interesting, especially "physics", and his learning progress was often ahead of the teacher's lecture progress.

 

With excellent results, Duan Luming got into Tongcheng High School, the best high school in Tongcheng City. Given his interest and talent in physics, he often represented his school in various provincial and national physics competitions during his high school years, often winning good grades. Because of these competitions, Duan Luming became so famous that many colleges and universities offered him an "olive branch", hoping to invite him to study at their schools.

 

02The "Duan-Guo Limit" was created by being guaranteed admission to the University of Science and Technology of China

 

In 1990, the University of Science and Technology of China (USTC) granted Duan Luming an exemption from the entrance exams, allowing him to study at the university directly after graduation.

 

During his college years, he chose quantum mechanics, a relatively cold major at that time. In the 1990s, there were very few people studying quantum mechanics, and many aspects were in a blank state, so it was very difficult to achieve something in this field. But Lu-Ming Duan felt that it was nothing to take the path taken by others before him, but to make one's own way was the real skill.

 

Luming Duan (second from right) in the lab

 

In this way, Duan Luming spent eight years in the lab at CSU, from undergraduate to Ph. During his doctoral studies, he published 40 papers one after another and solved many technical problems in physics. On the occasion of his PhD graduation, he unified his research and discoveries in the quantum field over the years and attached his own insights to form a PhD thesis, which was selected as one of the "100 Outstanding PhD Theses in China".

 

After his PhD, from 1999 to 2000, Lu-Ming Duan spent one year as a postdoctoral fellow at the Institute of Theoretical Physics, University of Innsbruck, Austria. In 2000, Lu-Ming Duan was selected as one of the "Hundred Talents Program" of the Chinese Academy of Sciences and returned to his alma mater, the University of Science and Technology of China, where he and his supervisor, academician Guang-Can Guo, achieved remarkable results in the field of probabilistic quantum cloning in just one year, which was called the "Duan-Guo limit". In 2001, at the age of 29, Lu-Ming Duan became one of the youngest Ph.D. and youngest professors at USTC, and even the president of USTC praised him: "Lu-Ming Duan is a born scientist."

 

03Studying in the U.S. in pursuit of excellence

 

In December 2001, when China had just joined the World Trade Organization and its economy had not yet fully taken off, the country's main focus was more on economic development and promoting people's livelihood, and not much attention was devoted to scientific research, so Lu-Ming Duan decided to go abroad again to learn more advanced quantum theory. This trip is ten years.

 

Duan's first stop in the United States was the California Institute of Technology, where he spent two years in a postdoctoral site studying quantum research. He was then appointed as an assistant professor at the University of Michigan, during which time he was published in Science and Nature, the leading journals in the academic world.

 

In 2007, at the age of 35, Luming Duan was hired as a tenured professor at the University of Michigan. In addition, Lu-Ming Duan was the first Chinese PhD recipient of the Sloan Prize.

 

Lecture by Lu-Ming Duan

 

04Eight years on the road back to China, but no less in the heart of research

 

Science has no national boundaries, but scientists have national boundaries. Returning to China is always Duan Luming's first choice.

 

After receiving a call from Prof. Yao Qizhi of Tsinghua University to return to China, Luming Duan submitted his resignation to the University of Michigan, but his journey back to China was not smooth, spanning a period of eight years. In 2017, Duan's team at Tsinghua University set a new international record for quantum storage capacity, achieving the first atomic quantum memory with 225 memory cells, raising the international record for quantum memory storage capacity by more than one This has improved the international record of quantum memory storage capacity by more than one order of magnitude.

 

In April 2019, he was appointed as the first Tsinghua University Chair in Basic Science.

 

During his tenure as a teacher, Lu-Ming Duan not only studied his own scientific work, but also taught his students the research results he had acquired over the years without reservation. He hopes that his students will become creative scientists and add to the quantum research in China.

 

05Returning to his homeland and building up his thinking

 

Many scientists find their own unique track in their research career, but Lu-Ming Duan has made achievements in all research fields.

 

In quantum machine learning, in 2017, Prof. Lu-Ming Duan and his PhD student Xun Gao discovered that deep neural networks and quantum many-body problems are closely related, and demonstrated that wave functions of almost all quantum many-body systems can be effectively represented using deep neural network models, demonstrating the great potential of neural networks and deep learning algorithms in quantum many-body problems. graduate students Xun Gao and Zhengyu Zhang discovered quantum machine learning algorithms with exponential acceleration, demonstrating the great potential of quantum computers in the field of artificial intelligence research; and proposed for the first time a quantum generation model based on optimized many-body quantum entangled states, and also demonstrated the exponential acceleration of this quantum generation model in terms of learning ability and prediction ability; and later also proposed heuristic quantum machine learning that can actually and effectively use this novel graph The heuristic quantum machine learning algorithm that can practically and effectively utilize this novel graph model, which transforms the inference and training problem of the generative model into the ground state preparation problem of quantum many-body Hamiltonian quantities, and thus can demonstrate the exponential acceleration of the quantum algorithm.

 

Schematic representation of deep neural network for quantum many-body wave function

 

In terms of fundamental research, Lu-Ming Duan's group and collaborators first observed the kinetic quantum phase transition corresponding to the many-body excited state in a sodium-atom-based Bose-Einstein condensate; then, the first theoretical extension of the phase transition kinetic (Kibble-Zurek) mechanism to the first-order quantum phase transition in a sodium-atom-based Bose-Einstein condensate, and experimentally observed this generalized Kibble-Zurek mechanism; and, the quantum Rabi model was simulated using a single imprisoned ion and the first quantum phase transition phenomenon was observed in this model.

 

In terms of quantum networks, in addition to the aforementioned setting an international record for quantum storage capacity, in 2018, Lu-Ming Duan's group achieved the first quantum entanglement between 25 independent quantum interfaces, which was highly praised by the reviewers of Science Advances as "a record number of entanglements and an important milestone in the process of building the first quantum network In 2019, quantum multiplexed storage technology was combined with communication photonic interface technology for the first time in an atomic system to distribute quantum entangled states over long distances, demonstrating the feasibility of building large-scale quantum relay networks in the future. In 2021, the first experimentally efficient entangled connection between two relay modules in a quantum relay protocol was achieved, successfully demonstrating the scale-up of the connection efficiency of quantum relay modules, a key step toward practical quantum relays; in the same year, on-demand access to quantum memory in the microwave band was achieved. 2022, the first experimentally efficient use of quantum memory for preparation of non-local map states, demonstrating the prospect of quantum memory applications in large-scale distributed systems for quantum information processing and quantum measurements.

 

In quantum simulations, Lu-Ming Duan's group has successfully implemented quantum simulations of two-dimensional exo-particles in a magnetic field using a single captive ion; the first experimental implementation of the Rabi-Hubbard model with the help of ion quantum bits, and verified the quantum phase transition and quantum dynamics processes of this model; the first experimental implementation of the large-scale Jaynes-Cummings-Hubbard (Jaynes-Cummings-Hubbard) model with the help of ion quantum bits. Cummings-Hubbard model, both of which surpass the simulation capabilities of existing classical supercomputers.

 

In quantum computing, in 2014, Lu-Ming Duan's group achieved the first noise-resistant geometric quantum computation in a room-temperature solid-state system. By using a new form of computation, "geometric quantum computation," quantum computation in room-temperature diamond systems is more resistant to the effects of noise; in 2019, Lu-Ming Duan's group and collaborators realized microwave photon binomial quantum error correction codes in superconducting quantum systems, the first time to achieve both quantum error correction of logical quantum bits In 2021, the first experimental study of the effect of environmental bits on Cross-resonance (CR) logic gates using a tunable coupled multi-quantum bit system was conducted and an experimental solution was proposed; in 2022, a double quantum bit code with coherent conversion was realized for the first time using homogeneous ions, thus overcoming the effect of crosstalk between multiple bits in quantum computing. In 2022, the first double quantum bit encoding was achieved using homogeneous ions, thus overcoming the effect of crosstalk between multiple bits in quantum computing, and verifying that the crosstalk error of the system in various quantum manipulation processes is significantly lower than the threshold required for quantum error correction. In the same year, Lu-Ming Duan's group successfully prepared the multi-body "Schrödinger cat" state of coherent flying microwave photons for the first time with the help of superconducting quantum circuits, and verified that the crosstalk between different "cat" states and the multi-body "cat" state and the superconducting quantum circuit are significantly lower than the threshold required for quantum error correction. The quantum entanglement between different "cat" states and superconducting "cat" states and superconducting quantum bits was verified.

 

Schematic diagram of binomial quantum error correction code

 

In addition to research in the quantum field itself, Luming Duan has also made important contributions to the development of key technologies for quantum information science. 2022, the team achieved the first efficient cooperative cooling of long ion chains by laser cooling of an optimally selected small number of ions to obtain a temperature close to the limit of global laser cooling, preparing the technical basis for multi-ion bit quantum computing. Recently, they also realized microwave single-photon triodes for the first time in experiments using superconducting quantum circuits and achieved gains of up to 53.4 dB and switching ratios of more than 20 dB, an improvement of several orders of magnitude compared to previous devices.

 

Lu-Ming Duan, a "genius" in the eyes of his teachers as a child, has grown into a "generalist" in the field of quantum science.