TY - JOUR ID - Charif2021 LB - Charif2021 AU - Charif, Mirna AU - Zielinski, Lech TI - Perturbation series for Jacobi matrices and the quantum Rabi model ST - Perturbation series for Jacobi matrices and the quantum Rabi model JO - Opuscula Math. JA - Opuscula Math. JF - Opuscula Mathematica PY - 2021 VL - 41 IS - 3 SP - 301 EP - 333 DO - https://doi.org/10.7494/OpMath.2021.41.3.301 UR - https://doi.org/10.7494/OpMath.2021.41.3.301 AB - We investigate eigenvalue perturbations for a class of infinite tridiagonal matrices which define unbounded self-adjoint operators with discrete spectrum. In particular we obtain explicit estimates for the convergence radius of the perturbation series and error estimates for the Quantum Rabi Model including the resonance case. We also give expressions for coefficients near resonance in order to evaluate the quality of the rotating wave approximation due to Jaynes and Cummings. KW - Jacobi matrix KW - unbounded self-adjoint operators KW - quasi-degenerate eigenvalue perturbation KW - perturbation series KW - quantum Rabi model KW - rotating wave approximation SN - 1232-9274 ER -