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Dispersive estimates for Schroedinger operators: A survey

Wilhelm Schlag

TL;DR

The article surveys dispersive estimates for Schrödinger evolutions $e^{itH}P_c$ with decaying real potentials across dimensions and in time-dependent settings. It synthesizes perturbative and spectral techniques, including Born series, resolvent expansions near zero energy, and the limiting absorption principle, to explain how zero-energy phenomena (eigenvalues and resonances) affect decay rates. The survey highlights dimension-specific results: in $d\ge3$ perturbative and large-potential regimes; in $d=1$ with sharp weighted decay when zero is not a resonance; in $d=2$ a first $L^1\to L^\infty$ bound with $|t|^{-1}$ decay under a regular-zero condition, via threshold-resolvent expansions. It also covers time-dependent potentials, Floquet theory, and charge-transfer models, connecting dispersive estimates to scattering theory and nonlinear stability questions in PDEs.

Abstract

We present some old and new results on dispersive estimates for Schroedinger equations.

Dispersive estimates for Schroedinger operators: A survey

TL;DR

The article surveys dispersive estimates for Schrödinger evolutions with decaying real potentials across dimensions and in time-dependent settings. It synthesizes perturbative and spectral techniques, including Born series, resolvent expansions near zero energy, and the limiting absorption principle, to explain how zero-energy phenomena (eigenvalues and resonances) affect decay rates. The survey highlights dimension-specific results: in perturbative and large-potential regimes; in with sharp weighted decay when zero is not a resonance; in a first bound with decay under a regular-zero condition, via threshold-resolvent expansions. It also covers time-dependent potentials, Floquet theory, and charge-transfer models, connecting dispersive estimates to scattering theory and nonlinear stability questions in PDEs.

Abstract

We present some old and new results on dispersive estimates for Schroedinger equations.

Paper Structure

This paper contains 5 sections, 7 theorems, 128 equations.

Key Result

Lemma 2.1

Let \psi be a smooth, even bump function with \psi(\lambda)=1 for -1\le\lambda\le 1 and \hbox{supp}(\psi)\subset[-2,2]. Then for all t\ge1 and any real a, where C only depends on \psi.

Theorems & Definitions (10)

  • Lemma 2.1
  • Lemma 2.2
  • proof
  • Theorem 2.3
  • proof
  • Theorem 2.4
  • Theorem 3.1
  • proof
  • Theorem 4.1
  • Lemma 4.2