The toric code is an "instant classic" model of interacting qubits on a 2D lattice first proposed by Alexei Kitaev in 1997 ( A. Y. Kitaev, Ann. Phys. 303, 2–30 (2003) ).
In K. J. Satzinger et al., Science 374 6572, 1237-1241 (2021) , we create toric code eigenstates on our quantum processor and explore their essential topological properties: long-range entanglement, anyonic excitations, and locally-indistinguishable degenerate states used as logical qubits. In the following example, we focus on understanding and creating a toric code ground state.