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OP-00443 Open

A resonance gap for arbitrary uniformly hyperbolic trapping in three dimensions

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Let $V \in C_c^\infty(\mathbb{R}^3; \mathbb{R})$ and $P_h = -h^2 \Delta + V$, and let $E > 0$ be a regular value of $p(x, \xi) = |\xi|^2 + V(x)$, with Hamiltonian flow $\Phi^t$. Let $$K_E = \bigl\{\rho \in p^{-1}(E) : \{\Phi^t(\rho) : t \in \mathbb{R}\} \text{ is bounded}\bigr\}$$ be the trapped set at energy $E$, and assume that it is compact and uniformly hyperbolic: over $K_E$ the tangent bundle of $p^{-1}(E)$ splits continuously and invariantly into the flow direction, a stable subbundle on which $|d\Phi^t v| \le C e^{-ct} |v|$ and an unstable subbundle on which $|d\Phi^{-t} v| \le C e^{-ct} |v|$, for $t \ge 0$. The resonances of $P_h$ are the poles of the meromorphic continuation of the cut-off outgoing resolvent $\chi (P_h - z)^{-1} \chi$, $\chi \in C_c^\infty(\mathbb{R}^3)$, from $\operatorname{Im} z > 0$ across the positive real axis. Nonnenmacher and Zworski proved a resonance-free strip of width proportional to $h$ near $E$, in every dimension, when the topological pressure of the unstable Jacobian on $K_E$ is negative at $1/2$. In dimension two, for potentials whose trapped set is hyperbolic and topologically one-dimensional, Vacossin proved a resonance-free region $\{|z - E| < Ch,\ -\delta h \le \operatorname{Im} z \le 0\}$ with no condition on the pressure.

Problem. Must there exist $\delta, \gamma, h_0 > 0$ such that $P_h$ has no resonance in $$\bigl\{z : |\operatorname{Re} z - E| < \delta,\ -\gamma h < \operatorname{Im} z \le 0\bigr\}$$ for $0 < h < h_0$?

Source: Zworski (2017), Conjecture 3, for operators with a compact hyperbolic trapped set on manifolds with an effective meromorphic continuation; stated by AIM — Open Applied Problems for Schrödinger operators with compactly supported potentials on ℝ³.

Imported from github.com/MColbrook/AIM.

Classification

Primary
SP — Spectral Theory
Secondary
AP, MP
Keywords
AIM Open Applied Problems, hyperbolic trapped sets, scattering resonances, semiclassical analysis

References

@article{zworski2017,
  author        = {Zworski, Maciej},
  title         = {Mathematical study of scattering resonances},
  journal       = {Bull. Math. Sci.},
  volume        = {7},
  number        = {1},
  year          = {2017},
  pages         = {1--85},
  doi           = {10.1007/s13373-017-0099-4},
  eprint        = {1609.03550},
  archivePrefix = {arXiv},
}
@article{nonnenmacher2009,
  author        = {Nonnenmacher, St{\'e}phane and Zworski, Maciej},
  title         = {Quantum decay rates in chaotic scattering},
  journal       = {Acta Math.},
  volume        = {203},
  number        = {2},
  year          = {2009},
  pages         = {149--233},
  doi           = {10.1007/s11511-009-0041-z},
  eprint        = {0706.3242},
  archivePrefix = {arXiv},
}
@article{vacossin2024,
  author        = {Vacossin, Lucas},
  title         = {Spectral gap for obstacle scattering in dimension 2},
  journal       = {Anal. PDE},
  volume        = {17},
  number        = {3},
  year          = {2024},
  pages         = {1019--1126},
  doi           = {10.2140/apde.2024.17.1019},
  eprint        = {2201.08259},
  archivePrefix = {arXiv},
}
@misc{aim-hyperbolic-trapping-resonance-gap-three-dimensions,
  author       = {Brunton, Steve and Colbrook, Matthew J. and de Hoop, Maarten V. and Stepaniants, George and Townsend, Alex and Ward, Rachel},
  title        = {{A resonance gap for arbitrary uniformly hyperbolic trapping in three dimensions}},
  howpublished = {AIM --- Open Applied Problems, GitHub repository},
  year         = {2026},
  url          = {https://github.com/MColbrook/AIM/blob/a153f469ee0ea64e876b2ad97c79d252c19a3e22/problems/432-hyperbolic-trapping-resonance-gap-three-dimensions.md},
  note         = {Entry 432 at commit a153f46, 2026-10-13},
}

Citing this problem

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OP-00443, "A resonance gap for arbitrary uniformly hyperbolic trapping in three dimensions", clopen.solutions.