Jiawei Mei - Southern University of Science and Technology, China
The toric code is a topological quantum error correcting code, and an example of a stabilizer code, defined on a two-dimensional spin lattice. It also represents the simplest example of topological order -- Z2 topological order that was first studied in the context of Z2 spin liquid. I will talk about our recent progress in the search for a toric code topological order in the kagome antiferromagnetic spin system. With strong quantum fluctuations and geometry frustrations, the kagome antiferromagnet may host a spin liquid ground state. The kagome spin liquid can be described in terms of a SU(2) symmetric tensor network wave function and the toric code topological order is identified by the modular matrices. I will report a new kagome spin liquid compound Cu3Zn(OH)6FBr which was predicted in our first-principles simulation and has been successfully synthesized in the experiments by the hydrothermal method. Both nuclear magnetic resonance and neutron scattering experiments confirm the spin gap when approaching zero temperature in this compound. Moreover, the spin-1/2 quantum number of spinons (fractionalized spin excitations) is also identified experimentally. Both our numerics and experiments directly support a gapped Z2-gauge (i.e. toric code) type kagome spin liquid.