Quantum aspects of spacetime: a quantum optics view of acceleration radiation and black holes

For the centennial of quantum mechanics, we offer an overview of the central role played by quantum information and thermalisation in problems involving fundamental properties of spacetime and gravitational physics. This is an open area of research still a century after the initial development of formal quantum mechanics, highlighting the effectiveness of quantum physics in the description of all natural phenomena. These remarkable connections can be highlighted with the tools of modern quantum optics, which effectively addresses the three-fold interplay of interacting atoms, fields, and spacetime backgrounds describing gravitational fields and noninertial systems. In this review article, we select aspects of these phenomena centred on quantum features of the acceleration radiation of particles in the presence of black holes. The ensuing horizon-brightened radiation (HBAR) provides a case study of the role played by quantum physics in nontrivial spacetime behaviour, and also shows a fundamental correspondence with black hole thermodynamics.