Quantum chaos in an ultrastrongly coupled bosonic junction

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).The semiclassical and quantum dynamics of two ultrastrongly coupled nonlinear resonators cannot be explained using the discrete nonlinear Schrödinger equation or the Bose-Hubbard model, respectively. Instead, a model beyond the rotating wave approximation must be studied. In the semiclassical limit this model is not integrable and becomes chaotic for a finite window of parameters. For the quantum dimer we find corresponding regions of stability and chaos. The more striking consequence for both semiclassical and quantum chaos is that the tunneling time between the sites becomes unpredictable. These results, including the transition to chaos, can be tested in experiments with superconducting microwave resonators. © 2014 American Physical Society.The authors acknowledge support from the European project PROMISCE, Spanish MINECO Projects No. FIS2011-25167 and No. FIS2012-33022, Gobierno de Aragón (FENOL group), and CAM research consortium QUITEMAD (S2009-ESP-1594).Peer Reviewe