CAREER:Superconductivity, fractionalization and quantum criticality in multilayer quantum simulator

Johns Hopkins University, Baltimore MD

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical research and education activities to explore new quantum materials. The projects utilize atomically thin two-dimensional materials as building blocks. A typical two-dimensional material is graphene, which consists of a single layer of carbon atoms arranged in the form of honeycomb. Inside the material, many electrons move together and strongly interact with each other. Combination of quantum effects and strong correlations between electrons can lead to novel phases with interesting material properties and potential technology applications. For example, a superconductor material can conduct electric current with zero resistance when it is cooled to sufficiently low temperature. Some quantum materials may be utilized to build a quantum computer. The PI will develop various strategies to realize new quantum phases by stacking two dimensional materials together to form multilayer systems. The multilayer materials not only have new properties unseen in the single layer case, but also enable better experimental control and characterization of the material properties. This award also supports the PI’s education and outreach activities. The PI will (1) include undergraduate students in the research program and host informal journal club seminar, (2) develop new course materials to incorporate modern research topics and (3) engage students from public high schools from underserved areas in Baltimore City in research. TECHNICAL SUMMARY This award supports theoretical research and education activities to explore novel quantum phases which can emerge in multilayer systems built from stacking the elementary two-dimensional layers as “Lego sets”. These projects will take advantage of the recent capability to exploit the layer degree of freedom in such materials. Various theoretical and numerical methods will be utilized, including parton mean field theory, quantum field theory and density-matrix-renormalization-group (DMRG) simulations. The studies will work closely with on-going and near future experiments in the three different platforms: (1) Novel phases of matter and their experimental signatures in bilayer moire superlattices; (2) Quantum criticality and non-Abelian fractional phases in quantum Hall bilayers; (3) Enhanced Superconductivity and Kondo transition in bilayer optical lattice. The project will develop new theoretical frameworks and numerical methods for strongly correlated models, benchmarked and refined by ongoing and near future quantum simulation experiments. The project can potentially lead to better understanding of the mechanism towards high temperature superconductors and development of new platforms for topological quantum computation. This proposal closely links research with support for diversity, education and community outreach. The proposal will develop new lecture notes and course materials for the course ‘Condensed Matter Physics’ to include modern research topics such as band topology and twisted bilayer graphene. The PI will include undergraduate students in the research program and encourage communications between undergraduate students, graduate students and postdocs by hosting an informal journal club seminar. The PI will also engage students from public high schools from underserved areas in Baltimore City in research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.