- Open Access
Probing Stringy Horizons with Pole Skipping in Nonmaximal Chaotic Systems
Phys. Rev. Lett. 137, 051602 – Published 28 July, 2026
DOI: https://doi.org/10.1103/cvjn-7kvp
Abstract
In this Letter, we study pole skipping in nonmaximally quantum chaotic systems. Using Rindler conformal field theories and the large- Sachdev-Ye-Kitaev chain as illustrative examples, we argue that the pole skipping points of few-body operators organize into trajectories in the complex frequency-momentum plane, with the leading trajectory encoding the quantum Lyapunov exponent. We further propose that these trajectories admit a natural interpretation as Regge trajectories of stringy excitations in a dual stringy black-hole geometry. From this perspective, pole skipping for an individual operator can be viewed as tracking the stringy horizon through the response of a single excitation. Our results suggest that pole skipping reflects intrinsic properties of quantum chaotic systems and may be deeply connected to the structure of horizons in the stringy regime.
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Supplemental Material
References (62)
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Pole skipping of bulk higher-spin fields in AdS black holes has been previously studied in [18]. Owing to the highly involved nature of the bulk equations, only partial results were obtained. We will compare our findings with theirs below.
We relegate the details to Sec. S-I of Supplemental Material [34] and present only the final results here.
- See Supplemental Material at http://link.aps.org/supplemental/10.1103/cvjn-7kvp for the details of the derivation of the pole skipping of a spin operator and a composite operator, and the Hamiltonian of SYK chain, which includes Refs. [26,35–42].
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Although there is no translation symmetry along the radial direction in hyperbolic space, it is nevertheless possible to define ; see Sec. S-I of Supplemental Material [34].
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More generally, one can define the velocity-dependent Lyapunov exponent [52] for OTOC with large spacetime separation with . It is given by the saddle-pole transition on the leading Regge trajectory [29]. In the pole-dominant regime, the velocity-dependent Lyapunov exponent is ballistic , where is the butterfly velocity. The pole-dominant regime can be determined by the pole skipping of stress tensor at (4) with . Therefore, all quantum chaotic data of OTOC can be extracted from pole skipping.
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We mention by passing that it appears natural to conjecture that the first line of (6) corresponds to “descendants” of the highest pole skipping points, arising from the same underlying horizon symmetries, while the second line originates from a different physical mechanism.
For the highest pole skipping points, an explanation for this universality is their origin from horizon symmetries.
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In Sec. S-II of Supplemental Material [34], we give a precise definition of composite operators in a generic theory and study their pole skipping behavior in the Rindler CFT, where additional pole skipping points are observed, potentially attributable to nonlocal intermediate operators. We leave elucidation of their origin to future work.
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We should choose the solution of for .
, which is also precisely the momentum-dependent Lyapunov exponent discussed by [26].
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