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Spectral transitions in some Rabi models

Grzegorz Świderski, Lech Zieliński

Abstract

We consider the transition from discrete to continuous spectrum which occurs in some quantum Rabi models. The subordinacy theory is used to detect and locate the essential spectrum of the intensity-dependent Rabi model, the anisotropic two-photon Rabi model, and the two-photon Rabi-Stark model for the whole range of parameters. The absence of a singular spectrum and the absence of eigenvalues in the interior of the essential spectrum are proved for all models considered.

Spectral transitions in some Rabi models

Abstract

We consider the transition from discrete to continuous spectrum which occurs in some quantum Rabi models. The subordinacy theory is used to detect and locate the essential spectrum of the intensity-dependent Rabi model, the anisotropic two-photon Rabi model, and the two-photon Rabi-Stark model for the whole range of parameters. The absence of a singular spectrum and the absence of eigenvalues in the interior of the essential spectrum are proved for all models considered.
Paper Structure (34 sections, 12 theorems, 115 equations)

This paper contains 34 sections, 12 theorems, 115 equations.

Key Result

Theorem 2.1

The operator $H$ is unitarily similar to the direct sum where $J^\pm =J((a_n ),(b_n^\pm ))$ is the Jacobi operator with The operator $J^\pm$ is self-adjoint in $\ell^2(\mathbb{N}_0)$ and Moreover, in all cases, $\sigma_{\mathrm{sc}}(J^\pm) = \emptyset$, and $\sigma_{\mathrm{p}}(J^\pm)$ is disjoint from the interior of $\sigma_{\mathrm{ac}}(J^\pm)$.

Theorems & Definitions (16)

  • Theorem 2.1
  • Theorem 2.2
  • Theorem 2.3
  • Theorem 2.4
  • Theorem 3.1: Carleman
  • Corollary 3.2
  • proof
  • Proposition 3.3
  • Proposition 3.4
  • proof
  • ...and 6 more