Homequant-pharXiv:2605.29959

Quantitative semidefinite certificates for ground-state energies of Pauli Hamiltonians

quant-phmath.OC2026-05v1license

Abstract

The kk-local Hamiltonian problem is a central model for quantum many-body systems and Hamiltonian complexity. Semidefinite programming and noncommutative sum-of-squares hierarchies provide systematic certificates for ground-state energies, but existing finite-convergence results give no quantitative guarantee on the accuracy of the low hierarchy levels accessible in computation. We prove explicit finite-level convergence rates for these hierarchies in the Pauli setting. For kk-local Hamiltonians whose Pauli expansion contains only even-weight terms, we show that both the NPA-type lower-bound hierarchy and the upper-bound hierarchy on the spectral minimum have error at most C(k)ξd+1n,4/nC(k)\xi^{n,4}_{d+1}/n, where ξd+1n,4\xi^{n,4}_{d+1} is the smallest root of a Krawtchouk polynomial and C(k)C(k) is independent of the number of qubits nn and the hierarchy level dd. General kk-local Hamiltonians reduce to this even-weight case by adding one ancilla qubit while preserving the spectrum. The proof constructs almost-reproducing kernels for the Pauli algebra and relates their spectra to Krawtchouk polynomials, giving a noncommutative analogue of recent kernel-based convergence analyses for commutative polynomial optimization. These results provide the first quantitative finite-level accuracy guarantees for noncommutative semidefinite relaxations of Pauli Hamiltonians.

Comments: 20 pages, 1 figure

Cite

@article{arxiv.2605.29959,
  title  = {Quantitative semidefinite certificates for ground-state energies of Pauli Hamiltonians},
  author = {Igor Klep and Nando Leijenhorst and Victor Magron},
  journal= {arXiv preprint arXiv:2605.29959},
  year   = {2026}
}