Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics

When ground-state atoms are accelerated through a high $Q$ microwave cavity, radiation is produced with an intensity which can exceed the intensity of Unruh acceleration radiation in free space by many orders of magnitude. The reason is a strong nonadiabatic effect at cavity boundaries and its interplay with the standard Unruh effect. The cavity field at steady state is still described by a thermal density matrix under most conditions. However, under some conditions gain is possible, and when the atoms are injected in a regular fashion, squeezed radiation can be produced.

Figure 1

(a) Atoms in the ground state $|b⟩$ are accelerated through small holes in the corner reflectors of a microwave (or optical) cavity by, e.g., a strong gravitational field. This is depicted as a unidirectional, single mode, ring cavity to convey the idea. (b) “Vibrating reed” piezoelectrically driven oscillator containing a two-level atom is placed in the cavity yielding strong mazer action. (c) Parametric conversion of vibronic energy $p\hslash {\omega }_{\mathrm{o}}$ into photon and atom energies $\hslash \nu$ and $\hslash \omega$, respectively. (d) An atom is excited (deexcited) as it simultaneously absorbs (emits) a photon in a resonant process. (e) The counter-resonant processes that are usually neglected as compared to the resonant processes in the “rotating wave” approximation; i.e., an atom is excited (deexcited) as it simultaneously emits (absorbs) a photon.