Wen Xiaogang is a well-known physicist, a member of the National Academy of Sciences, a tenured professor at the Massachusetts Institute of Technology, and a Green Chair Professor. His main research interests are: condensed matter physics. In 2002, he was elected a fellow of the American Physical Society. In 2017, he received the Buck Prize from the American Physical Society.
In 1977, Wen Xiaogang was admitted to the Department of Physics of the University of Science and Technology of China, and in 1981, he passed the CUSPEA (Sino-US Joint Physics Graduate Program) entrance examination with the first place in the country, and then went to Princeton University for further study, and received a doctorate degree from Princeton University in 1987.
1 .It's fun, it's beautiful math".
In his famous speech "Innovation is a Child's Game", Wen Xiaogang introduced in detail the discovery process of his new theory of condensed matter physics.
Wen Xiaogang said: "After graduating from graduate school in 1987, I switched from superstrings to condensed matter physics. At that time, a condensed matter physicist said to me sympathetically and pityingly: Now when I turn to condensed matter physics, there is nothing to do. At that time, I was ignorant, and I didn't take it to heart. After changing direction, I was initially interested in quantum spin liquids in high-temperature superconductivity because I thought it was fun, and because I thought it was mathematically beautiful, challenging, and very different from the way of thinking in standard condensed matter physics. ”
2 .Discover the Topological Phase (topological order).
In 1989, Wen Xiaogang realized that different chiral spin liquid phases can have complete phase symmetry, which means that these differences cannot be distinguished and described by Landau's symmetry breaking theory. The quantum Hall phase that I saw later cannot be described by Landau's symmetry breaking theory. These are completely new phases of matter that have not been seen before. Wen Xiaogang called this new type of material phase topological phase (also known as topological state of matter). Placing a state of matter in a space with different topological connections allows the topological order of the state of matter to be detected. Topological states of matter as a new characterization: because the state of matter is placed in a space with different topological connectivity, the relationship between the ground state degeneracy and the spatial topology of the state of matter is used to describe the topological order in the state of matter. But this new portrayal was not recognized at first.
3 .Topological Order: Higher-Order Categories.
Ten years later, quantum information became a very thriving field and began to influence condensed matter physics. At this time, Wen Xiaogang discovered that the topological order in the topological state of matter turned out to be different configurations of quantum entanglement. "I remember when I realized this in 2002, I suddenly had a clarity in my head," he recalls. For me, this is a transition from not knowing to not knowing, to knowing and not knowing, which has raised my understanding of topological order to a higher level. I used to have the name "topology", but I didn't really know what a topology was. ”
Later, Wen Xiaogang realized that the topological order is equal to the configuration of many-body quantum entanglement. This understanding leads to the higher-order category-based theory of topological order. Higher-order categories is a purely mathematical theory that most mathematicians don't care about, and it's a developing theory. In order to systematically describe topological orders in condensed matter physics, it is necessary to further develop higher-order category theory in mathematics. Wen Xiaogang believes that it is the first time since Newton that the frontiers of physics and mathematics have come into close contact.
4 .Interactions, Information and Matter: "The Great Unified Theory".
If space is a sea of qubits with a string-net entanglement structure (a new type of quantum ether), this could explain the origin of all elementary particles. This represents a unity of information and matter. The sea of qubits that make up space is also a topological state of matter with a topological order. The topological order and its corresponding quantum entanglement are the origin of photons, electrons, and all other elementary particles. This has been mathematically proven to be possible. The current standard grand unification theory only unifies the three interactions. The topological state of matter is a super-large unified theory that unifies interactions, information, and matter. Topological states of matter have become one of the most active frontiers in condensed matter physics.
Finally, Wen Xiaogang confidently pointed out: "People are looking for a variety of materials to achieve a variety of different topological sequences. If we find a material that implements the topological order of the string network in the sea of space qubits, then this material can simulate all elementary particles. With this material in our hands, we can claim to have mastered the world. ”