Entanglement amplification from rotating black holes

The quantum vacuum has long been known to be characterized by field correlations between spacetime points. We show that such correlations-vacuum entanglement-in the environment of near-extremal black holes is significantly amplified (up to ten-fold) relative to their slowly rotating counterparts. We demonstrate this effect for rotating Banados-Teitelboim-Zanelli black holes by measuring the entanglement through the concurrence extracted from the vacuum via two-level quantum systems (Unruh-DeWitt detectors). The effect is manifest at intermediate distances from the horizon, and is most pronounced for near-extremal small mass black holes. The effect is also robust, holding for all boundary conditions of the field and at large spacelike detector separations. Smaller amplification occurs near the horizon, where we find that the entanglement shadow-a region near the black hole from which entanglement cannot be extracted-is diminished in size as the black hole's angular momentum increases.