%0 Electronic Article
%A Xu, Xuexin
%A Kaur, Kuljeet
%A Vignes, Chloé
%A Ansari, Mohammad H.
%A Martinis, John M.
%T Surface-Code Hardware Hamiltonian
%N arXiv:2507.06201
%M FZJ-2025-04654
%M arXiv:2507.06201
%D 2025
%Z 18 pages, 12 figures
%X We present a scalable framework for accurately modeling many-body interactions in surface-code quantum processor units (QPUs). Combining a concise diagrammatic formalism with high-precision numerical methods, our approach efficiently evaluates high-order, long-range Pauli string couplings and maps complete chip layouts onto exact effective Hamiltonians. Applying this method to surface-code architectures, such as Google's Sycamore lattice, we identify three distinct operational regimes: computationally stable, error-dominated, and hierarchy-inverted. Our analysis reveals that even modest increases in residual qubit-qubit crosstalk can invert the interaction hierarchy, driving the system from a computationally favorable phase into a topologically ordered regime. This framework thus serves as a powerful guide for optimizing next-generation high-fidelity surface-code hardware and provides a pathway to investigate emergent quantum many-body phenomena.
%F PUB:(DE-HGF)25
%9 Preprint
%U https://juser.fz-juelich.de/record/1048448