Chinese scientists have achieved new breakthroughs in key core technologies in many frontier scientific and technological fields
For the first time in my country, triatomic molecules are synthesized in ultra-cold atomic and molecular gas mixtures
Pan Jianwei, Zhao Bo and others from the University of Science and Technology of China cooperated with Bai Chunli's group from the Institute of Chemistry, Chinese Academy of Sciences to synthesize triatomic molecules for the first time in an ultracold atomic-molecular mixture, which is a step toward the research of quantum simulation and ultracold quantum chemistry based on ultracold atoms and molecules important step.
The results were published in Nature on February 10.
Quantum computing and quantum simulation have powerful parallel computing and simulation capabilities, which can not only solve computational problems that classical computers cannot handle, but also effectively reveal the laws of complex physical systems, thus providing guidance for new energy development, new material design, etc.
The use of highly controllable ultracold quantum gas to simulate complex and difficult-to-compute physical systems enables accurate and comprehensive research on complex systems, and thus has broad application prospects in chemical reactions and new material design.
Ultracold molecules will open new ideas for realizing quantum computing and provide an ideal platform for quantum simulations.
However, it is very difficult to prepare ultracold molecules by direct cooling due to the complex vibrational and rotational energy levels inside the molecules.
The development of ultracold atom technology provides a new way to prepare ultracold molecules.
One can bypass the difficulty of directly cooling molecules and use lasers, electromagnetic fields, etc. to synthesize molecules from ultracold atomic gases.
The synthesis of triatomic molecules from the mixture of atoms and diatomic molecules is an important research direction in the field of synthetic molecules.
For the first time in 2019, a research team from the University of Science and Technology of China observed Feshbach resonances of atoms and diatomic molecules at ultra-low temperatures.
Near the Feshbach resonance, the energy of the bound state of the triatomic molecule and the energy of the scattered state tend to be consistent, and the coupling between the scattered state and the bound state is greatly enhanced by resonance.
The successful observation of atomic and molecular Feshbach resonance provides a new opportunity for the synthesis of triatomic molecules.
In this study, the research team of the University of Science and Technology of China and the research team of the Institute of Chemistry, Chinese Academy of Sciences have successfully realized the coherent synthesis of triatomic molecules using radio frequency fields for the first time.
In the experiment, they prepared a sodium-potassium ground-state molecule in a single hyperfine state from an ultracold atomic mixture near absolute zero.
In the vicinity of the Feshbach resonance of potassium atoms and sodium-potassium molecules, the scattering states of atomic molecules and the bound states of triatomic molecules are coupled together by a radio frequency field.
They successfully observed the RF-synthesized triatomic molecule signal on the RF loss spectrum of sodium-potassium molecule, and measured the binding energy of the triatomic molecule near the Feshbach resonance.
This achievement opens up a new avenue for research in quantum simulation and ultracold chemistry.
Chinese scientists establish a new method for de novo protein design
Based on the data-driven principle, the team of Professor Liu Haiyan and Associate Professor Chen Quan of the University of Science and Technology of China has opened up a new route of protein de novo design, and realized the original innovation of key core technologies in the frontier science and technology field of protein design. The design of functional proteins such as biomedical proteins has laid a solid foundation.
The related results were published in Nature on February 10, Beijing time.
Protein is the basis of life and the main executor of life functions. Its structure and function are determined by amino acid sequence.
At present, almost all proteins that can form stable three-dimensional structures are natural proteins, and their amino acid sequences are formed by long-term natural evolution.
When the natural protein structure and function cannot meet the needs of industrial or medical applications, to obtain a specific functional protein, it is necessary to design its structure.
In recent years, the representative work of protein de novo design in the world mainly adopts RosettaDesign, which uses natural structural fragments as building blocks to splicing to generate artificial structures.
However, this method has the shortcomings of single design result and too sensitive to the details of the main chain structure, which significantly limits the diversity and variability of the designed main chain structure.
The relevant team of the University of Science and Technology of China has been deeply engaged in basic research and applied basic research in the direction of computational structural biology for a long time.
Academician Shi Yunyu is a pioneer in this field in China.
The team of Prof. Haiyan Liu and Associate Prof. Quan Chen has been committed to developing data-driven protein design methods for more than ten years.
The team first established an ABACUS model for designing amino acid sequences for a given backbone structure, and then developed a SCUBA model that can de novo design a new backbone structure when the amino acid sequence is pending.
Theoretical calculations and experiments have shown that the use of SCUBA to design the main chain structure can break through the limitation that only natural fragments can be used to splicing new main chain structures, thereby significantly expanding the structural diversity of de novo proteins, and even designing proteins that are different from known natural proteins. novel structure.
The "SCUBA model + ABACUS model" constitutes a complete tool chain for de novo design of artificial proteins with new structures and sequences. It is the only fully experimentally validated protein de novo design method outside of RosettaDesign, and complements it.
In the paper, the team reports high-resolution crystal structures of nine de novo engineered protein molecules, five of which have novel structures that differ from known native proteins.
The reviewers believe that the approach presented in this work is sufficiently novel and useful; designing proteins de novo is challenging, and the high-resolution design of 6 different proteins in this work is an important achievement, justifying this approach Running well.
Chinese scholars discover new electronic nematic phase in caged superconductors
A team composed of Chen Xianhui, Wu Tao and Wang Zhenyu from the University of Science and Technology of China recently discovered a new type of electronic nematic phase in the caged superconductor CsV3Sb5.
This finding not only provides important experimental evidence for understanding the anomalous competition between charge density waves and superconductivity in cage-mesh superconductors, but also provides new insights into the interweaving order that is closely related to unconventional superconductivity in correlated electron systems. research direction.
The related results were published in Nature on February 10.
The electron nematic phase widely exists in high-temperature superconductors, quantum Hall insulators and other electronic systems, and there is a close connection between high-temperature superconductivity and high-temperature superconductivity.
Exploring superconducting material systems with new structures to further study the relationship between superconductivity and various interweaving orders is an important research direction in the current field. One of the systems that has received much attention is the two-dimensional cage structure.
Theoretically predicts that two-dimensional caged systems can exhibit novel superconductivity and abundant electronic order states, but for a long time there is a lack of suitable material systems to realize their associated physics. The discovery of caged superconductors CsV3Sb5 provides a new way to explore this direction. research system.
In previous studies, Xianhui Chen's team has successfully revealed the in-plane triple-modulated charge density wave state in this system, as well as the anomalous competition between charge density waves and superconductivity under pressure.
On this basis, the team combined scanning tunneling microscopy, nuclear magnetic resonance and elastic resistance three experimental techniques to find that before the system enters the superconducting state, the triple modulated charge density wave state will further evolve into a thermodynamically stable electron nematic phase. And determined that the transition temperature was around 35 Kelvin.
The new electron nematic phase has Z3 symmetry and is theoretically described by the three-state Potts model, so it is also called "Potts" nematic phase.
Interestingly, this new electronic nematic phase has also been recently observed in bilayer corner graphene systems.
This result not only reveals a new type of electron nematic phase in cage-mesh superconductors, but also provides experimental evidence for understanding the competition between superconductivity and charge density waves in such systems.
Previous scanning tunneling spectroscopy studies have shown that there may be paired density wave states (PDWs) in the CsV3Sb5 system, where superconductivity and charge density wave order are intertwined.
The electron nematic sequence found above the superconducting transition temperature can be understood as a PDW-related interweaving sequence, and this result also provides important clues and ideas for understanding PDW in high-temperature superconductors.
(Headquarters reporter Wang Li)