For the first time, the continent synthesized triatomic molecules in a mixture of ultracold atoms and molecules
Pan Jianwei and Zhao Bo of the University of Science and Technology of China cooperated with the Bai Chunli group of the Institute of Chemistry of the Chinese Academy of Sciences to synthesize triatomic molecules for the first time in the mixture of ultracold atoms and molecules, taking an important step towards quantum simulation based on ultracold atoms and molecules and the research of ultracold quantum chemistry. 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, thereby providing guidance for new energy development and new material design. The use of highly controllable ultra-cold quantum gases to simulate complex and difficult-to-calculate physical systems allows for accurate and all-round study of complex systems, thus having a wide range of application prospects in chemical reactions and new material design.
Schematic of the synthesis of triatomic molecules using radio frequency fields from a mixture of ultracold atoms and diatomic molecules
Ultracold molecules will open up new ideas for quantum computing and provide an ideal platform for quantum simulations. However, due to the complexity of the vibrational rotational energy levels inside the molecules, it is very difficult to prepare ultracold molecules by direct cooling. The development of ultracold atom technology provides a new way to prepare ultracold molecules. One can bypass the difficulty of direct cooling molecules and synthesize molecules from ultracold atomic gas using lasers, electromagnetic fields, etc. Synthesizing triatomic molecules from a mixture of atoms and diatomic molecules is an important research direction in the field of synthetic molecules.
The Research Team at the University of Science and Technology of China observed the Feshbach resonance of atoms and diatomic molecules at ultra-low temperatures for the first time in 2019. Near the Feshbach resonance, the energies of the bound state of the triatomic molecules tend to coincide with the energy of the scattering state, while the coupling between the scattered and bound states is greatly enhanced by resonance. The successful observation of the resonance of atomic molecules Feshbach provides new opportunities 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 of the Chinese Academy of Sciences cooperated to successfully realize the synthesis of triatomic molecules using radio frequency field coherence for the first time. In the experiment, they prepared sodium-potassium ground-state molecules in a single ultra-fine state from an ultra-cold atomic mixture close to absolute zero. Near the Feshbach resonance of potassium atoms and sodium-potassium molecules, the scattered states of atomic molecules and the bound states of triatomic molecules are coupled together by an RF field. They successfully observed the signal of the RF synthesis triatomic molecule on the rf loss spectrum of the sodium-potassium molecule and measured the binding energy of the triatomic molecule near the Feshbach resonance. This achievement opens up a new path for quantum simulation and the study of ultracool chemistry.
Mainland scientists built new methods for designing proteins from scratch
Based on the principle of data drive, 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 protein design route from scratch, realized the original innovation of key core technologies in the frontier technology field of protein design, and laid a solid foundation for the design of functional proteins such as industrial enzymes, biological materials, and biomedical proteins. The relevant results were published in Nature on February 10, Beijing time.
Proteins are the basis of life and the main performers of life functions, and their structure and function are determined by the sequence of amino acids. At present, proteins that can form a stable three-dimensional structure are almost all natural proteins, and their amino acid sequences are naturally evolved over a long period of time. When the structure and function of a natural protein do not meet the needs of industrial or medical applications, the structure of a specific functional protein needs to be designed. In recent years, the representative work of protein de novo design in the world has mainly adopted RosettaDesign , which uses natural structural fragments as building blocks to splice to produce artificial structures. However, this method has shortcomings such as single design results and excessive sensitivity to the details of the main chain structure, which significantly limits the diversity and variability of the design main chain structure.
The relevant team of the University of Science and Technology of China has long been deeply engaged in basic research and applied basic research in the direction of computational structural biology. Academician Shi Yunyu is a pioneer in this field in China. The team of Prof. Haiyan Liu and Associate Professor Quan Chen has been committed to developing data-driven protein design methods for more than a decade. The team first established an ABACUS model for designing amino acid sequences for a given backbone structure, and then developed an SCUBA model that can design a new backbone structure from scratch at the amino acid sequence waiting time. Theoretical calculations and experiments have proved that the design of the backbone structure with SCUBA can break through the limitation that only natural fragments can be used to splice to produce a new backbone structure, thereby significantly expanding the structural diversity of the de novo design proteins, and even designing novel structures that are different from known natural proteins. The "SCUBA Model + ABACUS Model" constitutes a complete tool chain for artificial proteins with a completely new structure and sequence from scratch, and is the only fully experimentally validated protein de novo design method outside of RosettaDesign, and complements it. In the paper, the team reported on the high-resolution crystal structures of 9 de novo designed protein molecules, 5 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 practical; designing proteins from scratch is challenging, and the high-resolution design of 6 different proteins in this work is an important achievement that proves that this method works well.
Chinese scholars have discovered novel electron facies in cage superconductors
A team of Chen Xianhui, Wu Tao and Wang Zhenyu of the University of Science and Technology of China recently discovered a new type of electron tropector in the cage superconductor CsV3Sb5. This finding not only provides important experimental evidence for understanding the abnormal competition between charge density waves and superconductivity in cage-structured superconductors, but also provides a new research direction for further studying the interleaved sequences in associated electronic systems that are closely related to unconventional superconductivity. The results were published in Nature on February 10.
Electron hoistine phases are widely present in electronic systems such as high-temperature superconductors and quantum Hall insulators, and there is a close relationship between high-temperature superconductivity, which is considered to be an interweaving sequence associated with high-temperature superconductivity. Exploring superconducting material systems with new structures, so as to further study the relationship between superconductivity and various interleaving sequences, is an important research direction in the current field, and one of the most concerned systems is two-dimensional cage structure. The theory predicts that the two-dimensional cage system can present novel superconductivity and rich electron ordered state, but for a long time there is a lack of suitable material systems to achieve its associated physics, and the discovery of the cage superconductor CSV3Sb5 provides a new research system for the exploration of this direction.
Physical diagram of electron sequence and superconductivity caused by triple modulated charge density waves in a cage structure superconductor
In the previous study, Chen Xianhui's team has successfully revealed the charge density wave state of the triple modulation in the surface of the system, and the abnormal competition relationship between the charge density wave and the superconductivity under pressure.
On this basis, the team combined three experimental techniques of scanning tunneling microscopy, nuclear magnetic resonance and elastic resistance, and found that before the system entered the superconducting state, the triple modulation charge density wave state would further evolve into a thermodynamically stable electron facade, and determined that the transition temperature was around 35 Kelvin. The new electron contiguous phase has Z3 symmetry, which is theoretically described by the three state Potts model, and is therefore also known as the "Potts" contiguous phase. Interestingly, this new electron-oriented phase has also recently been observed in bilayer angled graphene systems.
This achievement not only reveals a new electron facade in the cage structure superconductor, but also provides experimental evidence for understanding the competition between superconductivity and charge density waves in such systems. Previous scanning tunnel spectroscopy studies have shown that there may be paired density wave states (PDW) formed by the interweaving of superconductivity and charge density wave sequences in CsV3Sb5 systems. The electron sequence found above the superconducting transition temperature can be understood as an interleaved sequence associated with PDW, and this result also provides important clues and ideas for understanding PDW in high-temperature superconductors.
Source: CCTV News