$T^2$ deformations in the double-scaled SYK model: Stretched horizon thermodynamics

TL;DR

This paper explores T^2-deformations in the double-scaled SYK model, revealing how these deformations relate to the bulk geometry's stretched horizon, thermodynamic phase transitions, and rapid information scrambling.

Contribution

It introduces a finite cutoff interpretation of T^2-deformations in DSSYK, connecting it to the stretched horizon and analyzing resulting thermodynamic phase transitions.

Findings

The energy spectrum and entropy are well-defined near the stretched horizon.

A phase transition from stable to unstable thermodynamic states occurs with temperature variation.

The system exhibits enhanced growth and hyper-fast scrambling near the stretched horizon.

Abstract

It has been recently realized that the bulk dual of the double-scaled SYK (DSSYK) model has both positive and negative Ricci curvature and is described by a dilaton-gravity theory with a $\sin(\Phi)$ potential arXiv:2404.03535. We study T$^2$-deformations in the DSSYK model after performing the ensemble averaging to probe regions of positive and approximately constant curvature. The dual finite cutoff interpretation of the deformation allows us to place the DSSYK model in the stretched horizon of the bulk geometry, partially realizing a conjecture of Susskind arXix:2109.14104. We show that the energy spectrum and thermodynamic entropy are well-defined for a contour reaching these regions. Importantly, the system displays a phase transition from a thermodynamically stable to an unstable configuration by varying its microcanonical temperature; unless it is located on any of the stretched horizons, which is always unstable. The thermodynamic properties in this model display an enhanced growth as the system approaches the stretched horizon, and it scrambles information at a (hyper)-fast rate.