TY  - EJOUR
AU  - Xu, Xuexin
AU  - Kaur, Kuljeet
AU  - Vignes, Chloé
AU  - Ansari, Mohammad H.
AU  - Martinis, John M.
TI  - Surface-Code Hardware Hamiltonian
IS  - arXiv:2507.06201
M1  - FZJ-2025-04654
M1  - arXiv:2507.06201
PY  - 2025
N1  - 18 pages, 12 figures
AB  - 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.
LB  - PUB:(DE-HGF)25
UR  - https://juser.fz-juelich.de/record/1048448
ER  -