Harry C. and Olga K. Wiess Professor of Physics and Astronomy
- B.S., University of Science and Technology of China, 1986
- Ph.D., University of Chicago, 1991
- Alfred P. Sloan Research Fellow
- Humboldt Research Award
- Fellow, Institute of Physics (U.K.)
- Fellow, AAAS (American Association for the Advancement of Science)
- Fellow, American Physical Society
- Ulam Distinguished Scholar, Los Alamos National Laboratory
- Phone: 713-348-5204; Fax: 713-348-4150
Department of Physics and Astronomy
- Department of Physics and Astronomy
- Smalley-Curl Institute
- Wiess School of Natural Sciences
- Rice Center for Quantum Materials
- Condensed Matter Physics @ Rice University
- Condensed Matter Seminars
- Keck Program in Quantum Materials
- Recent publications – search arxiv.org
Theoretical Condensed matter physics, specializing in strongly correlated electron systems: quantum criticality and emergent phases, iron-based high temperature superconductivity, topological metals driven by strong correlations.
Qimiao Si is the Harry C. and Olga K. Wiess Professor of Physics and Astronomy at Rice University. He came to the United States through the highly selective CUSPEA program in 1986, upon earning his B.S. in Physics from the University of Science and Technology of China. He received his Ph.D. in Physics in 1991 from the University of Chicago and subsequently did postdoctoral work at Rutgers University and University of Illinois at Urbana-Champaign. He has been on the faculty of Rice University since 1994 (making the actual move to Rice in 1995, after a year’s leave of absence).
Prof. Si works in the field of theoretical condensed matter physics. His major contributions have been in the area of strongly correlated electron systems, including quantum criticality and emergent quantum phases, magnetic heavy fermion metals, high temperature iron-based superconductivity, strongly correlated topological metals, and mesoscopic and disordered electronic systems.
He is particularly well known for his contributions to the theory of quantum criticality, which concerns the physics of matter undergoing a transition from one quantum state to another. He introduced and developed the theory of local quantum criticality, which involves the notion of critical destruction of Kondo entanglement. The theory goes beyond the Landau framework, and has received extensive support from experiments in magnetic heavy fermion systems. He has made seminal contributions to the field of iron-based superconductors, contributing broadly to the understanding of electron correlations, quantum criticality, magnetism and superconductivity. In the area of topological states driven by strong correlations, he has advanced a Weyl-Kondo semimetal state. He has introduced the Bose-Fermi Kondo model and the method of the extended dynamical mean field theory, and contributed to the early development of the dynamical mean field theory. Other topics he has studied include the spin dynamics of the high temperature cuprate superconductors, metal-insulator transition in disordered and interacting electrons in two dimensions, experimental signatures of spin-charge separation, non-Fermi liquid states in an extended Hubbard model and in quantum impurity systems, and Mott transition between metallic and correlated insulating phases of interacting electrons.
Prof. Si was named a Sloan Research Fellow in 1996, and received a Cottrell Scholar Award from the Research Corporation for Science Advancement in 1998. He was elected a Fellow of the British Institute of Physics in 2004, the American Physical Society in 2005, and the American Association for the Advancement of Science in 2008. He received a Humboldt Prize from the Alexander von Humboldt Foundation in 2012, and was named a Ulam Distinguished Scholar by the Center for Nonlinear Studies of Los Alamos National Laboratory in 2018.
As of December 2018, he has published over 200 scientific articles (including 26 in Science, Nature, Nature Group Journals and PNAS, and 47 in Physical Review Letters) and has given more than 350 invited talks (including over 180 at conferences) on his research. He has served as a General Member on the Board of the Aspen Center for Physics (since 2009) and as a Member of the Advisory Editorial Board of Journal of Physics – Condensed Matter (2002-2006), and has co-chaired a number of international conferences and workshops, including the 2007 International Conference on Strongly Correlated Electron Systems (SCES’07), the 2014 KITP Program on Magnetism, Bad Metals and Superconductivity — Iron Pnictides and Beyond, and the 2018 Aspen Winter Conference on High Temperature Superconductivity — Unifying Themes in Diverse Materials.
Qimiao Si works in theoretical condensed matter physics, with an emphasis on quantum magnetism and superconductivity of strongly correlated electron systems.
Strongly correlated electron systems are at the forefront of condensed matter physics. Their theoretical description is a challenge that provides rich opportunities for creative research. The fundamental question is how the electrons are organized, and, in particular, whether there are principles that are universal among the various classes of these strongly correlated materials. The overarching goal of the group’s research is to seek such principles of universality. Along the way, it is also fascinating to explore the diversity of the phenomena that result from electron correlations.
One area of Prof. Si’s current interest is quantum criticality. He and his collaborators have advanced a by now well-known theory of local quantum criticality. Developed in the context of magnetic heavy fermion metals, which is a prototype system for quantum phase transitions, this theory features the “beyond-Landau” physics of critical Kondo destruction. A related topic of his recent research addresses novel phases that emerge in the vicinity of quantum critical points; for heavy fermion systems, his work here appears in the form of a proposed global phase diagram. He has also been interested in quantum critical physics in a variety of other contexts.
Another focus of Prof. Si’s ongoing research concerns iron-based superconductors. One important aspect of the work is to address the bad-metal behavior in the normal state, which is attributed to a proximity to delocalization-localization transition. This line of consideration has opened up studies on orbital-selective Mott phenomena. A corollary of this approach is that magnetism is primarily driven by J1-J2 interactions, a notion that he and his collaborators have pioneered. This approach has led them to theoretically predict a magnetic quantum critical point in iso-electronically tuned iron pnictides, which has been verified by extensive recent experiments. His recent work has also explored the related magnetic frustration physics in the iron chalcogenides, including its effect on the nematicity in FeSe. Finally, the implications of such magnetic interactions for the unconventional superconductivity is being studied; recent work along this direction has shown how high Tc superconductivity may develop in the iron chalcogenides with seemingly unfavorable Fermi-surface conditions, and how orbital selectivity gives rise to a new superconducting pairing state.
Yet another direction is on topological metals driven by strong correlations. His group has recently advanced a class of Kondo-driven Weyl semimetal state. Recent experiments in heavy fermion semimetals have provided thermodynamic and transport evidence for this Weyl-Kondo semimetal.
A variety of other topics on correlated electron systems are also of interest to the group. These range from non-Fermi liquid behavior, cuprate superconductivity, quantum entanglement in many-body systems, disordered and interacting electronic systems, metal-insulator transitions, out of equilibrium behavior of electronic systems, spin transport, and the probe of spin-charge separation.