Cavity-Induced Suppression of Entanglement and Enhancement of Quantum Discord

Abstract

We study correlations between two Unruh-DeWitt detectors coupled to a scalar field in a cylindrical cavity. Boundary conditions strongly modify the detector-correlation dynamics relative to free space. The entanglement negativity is suppressed in the cavity and vanishes for smaller separation as compared to the free space. Increasing the cavity radius does not recover the free-space behavior of the negativity. In contrast, mutual information and quantum discord remain nonzero over much larger separations. While the mutual information decays monotonically with separation, the quantum discord is enhanced near the cavity boundary. Our results demonstrate that geometric confinement can selectively suppress distillable entanglement while preserving and even enhancing more general non-classical correlations, providing a controlled setting to probe the hierarchy of correlations in quantum field theory.