arXiv subjects

Rafi Rizqy Firdaus

Publications and source records attributed to Rafi Rizqy Firdaus.

3 recordsLinked to original sources

arXiv2026

Holographic timelike entanglement and subregion complexity with scalar hair

We investigate the holographic timelike entanglement entropy (HTEE) and timelike subregion complexity of a thermal CFT$_d$ deformed by a relevant scalar operator $ϕ_0$, dual to a hairy black hole in AdS$_{d+1}$. We employ the prescription of merging spacelike and timelike surfaces at the interior, constructing an extremal surface homologous to a boundary timelike subsystem with a time interval $Δt$. Consequently, this deformation breaks the invariance of the imaginary component of HTEE observed in pure AdS$_3$ and BTZ geometry, introducing a nontrivial dependence on $Δt$. At small $Δt$, we derive analytical expressions that are in agreement with numerical results, and observe partial consistency with analytic continuation to temporal or spacelike entanglement entropy at the level of the near-boundary expansion. However, analytic continuation of CFT temporal entanglement entropy fails to reproduce the HTEE calculations under boundary deformation, even in $d=2$. Furthermore, we extend the numerical calculations to higher dimensions ($d=3$). In addition, we study holographic timelike subregion complexity within the complexity=volume conjecture and find that it remains real-valued, providing a complementary geometric probe of the black hole interior. In particular, for the BTZ black hole, we analytically show that the UV-finite term of the subregion complexity receives its entire contribution from the interior region alone.

hep-th↗

arXiv2025

Stationary Solution to Charged Hairy Black Hole in AdS4: Kasner Interior, Rotating Shock Waves, and Fast Scrambling

We consider a stationary solution of a charged black hole with scalar hair in AdS$_4$, where the scalar field is coupled to a $U(1)$ Maxwell gauge field. Near the singularity, the spacetime transitions into a more general Kasner geometry. The black hole is then injected with rotating and charged gravitational shock waves in the Dray-'t Hooft solution. These shock waves lengthen the wormhole connecting the two asymptotic boundaries, thereby disrupting the correlations between them. The correlation, quantified by the quantum mutual information between subregions on the left and right boundaries, vanishes at a characteristic timescale known as the scrambling time, which depends logarithmically on the black hole entropy. The mutual information is computed holographically using the Ryu-Takayanagi prescription for entanglement entropy. We investigate how the rotation and charge of both the black hole and the shock waves affect chaotic properties such as the scrambling time delay and the Lyapunov exponent. The interaction between the charges of the black hole and the shock waves introduces a delay in the scrambling process. We find that as the strength of the boundary deformation increases, both the Lyapunov exponent and the scrambling time delay decrease monotonically. Furthermore, the angular momentum of the shock waves enhances both the Lyapunov exponent and the scrambling time delay.

hep-th↗

arXiv2024

Discrete time scattering and Wold's decomposition in pictures

Based on explicit computations, various concepts of discrete time scattering theory are reviewed, discussed, and illustrated. The dynamics are taking place on a discrete half-space. All operators are represented graphically. The expressions obtained for the wave operators lead to an easily visualized interpretation of Wold's decomposition, a seminal result of operator theory. This work is clearly pedagogically oriented with the aim of providing explicit formulas and pictures for usually unexplicit operators.

math-ph↗