Abstract
We investigate the effects of a time-periodic, non-Hermitian, perturbation on a system with two (or few) levels, and obtain its phase diagram as a function of the perturbation strength and frequency. We prove that when the perturbation frequency is close to one of the system resonances, even a vanishingly small gain-loss potential leads to symmetry breaking. We also find a restored phase at high frequencies, and at moderate perturbation strengths, we predict the existence of multiple frequency windows where symmetry is broken and restored. Our results imply that the Rabi problem shows exceptionally rich phenomena absent in its Hermitian or static counterparts.
- Received 16 July 2014
DOI:https://doi.org/10.1103/PhysRevA.90.040101
©2014 American Physical Society