A holographic realization of correlation and mutual information
Ashis Saha, Anirban Roy Chowdhury, Sunandan Gangopadhyay
TL;DR
The paper investigates a finite-temperature, holographic realization of the information-theoretic bound $I(A:B) \ge \frac{(\langle O_A O_B\rangle_\beta - \langle O_A\rangle_\beta \langle O_B\rangle_\beta)^2}{2 \langle O_A^2\rangle_\beta \langle O_B^2\rangle_\beta}$ by embedding a large-$N$ QFT with Lifshitz dual into Lifshitz black hole geometries. Using geodesic approximations for heavy operators, it computes the thermal two-point function, thermal one-point function, and the composite operator norm $\langle O^2\rangle_\beta$ in various temperature regimes, and evaluates holographic mutual information for disjoint subsystems. The analysis reveals two characteristic separation scales, $sT|_c$ and $sT|_I$, separating quantum and classical correlation contributions, with $sT|_I > sT|_c$, and shows that the bound can be saturated or violated depending on how $\langle O^2\rangle_\beta$ is determined. The work highlights the sensitivity of information-theoretic inequalities to finite-temperature holographic data and underscores the role of thermal operator norms in diagnosing quantum versus classical correlations in strongly coupled systems.
Abstract
The status of the inequality existing between mutual information and (normalized) thermal two-point connected correlation function, namely, $I(A:B)\ge\frac{(\expval{\mathcal{O}_{A}\mathcal{O}_{B}}_β-\expval{\mathcal{O}_{A}}_β\expval{\mathcal{O}_{B}}_β)^2}{2\expval{\mathcal{O}_{A}^2}_β\expval{\mathcal{O}_{B}^2}_β}$ has been explicitly probed by using the gauge/gravity correspondence. In the holographic analysis, the geodesic approximation for heavy operators ($Δ\sim mR$) has been used. We observe that the study leads to some non-trivial insights depending upon the method of calculating the thermal object $\expval{\mathcal{O}^2}_β$. For a particular computed result of $\expval{\mathcal{O}^2}_β$ we propose that all of the existing quantum mechanical dependencies (correlations) and classical correlations between the subsystems $A$ and $B$ vanishes at two different separation lengths, namely, $sT|c$ and $sT|_I$ where $sT|_I>sT|_c$.
