Fuzzy spacetime: fundamental limits of quantum-optical holographic bulk reconstruction

Abstract: In this Essay we construct a concrete, non-perturbative realization of metric reconstruction using quantum-optical model of particle detectors in relativistic quantum information. The non-perturbative approach allows us to realize a version of "short-distance physics corresponds to poor statistics" idea by Kempf which occurs way above the Planck scale before one reaches the quantum-gravitational regime. In particular, the "fuzziness" of spacetime that arise from operational measurement protocols can be given a holographic dual interpretation using bulk-to-boundary correspondence between scalar correlators in asymptotically flat spacetimes. The holographic interpretation necessitates imperfect metric reconstruction even in principle due to the universality of future null infinity.