29 research outputs found
Nonlinear coherent destruction of tunneling
We study theoretically two coupled periodically-curved optical waveguides
with Kerr nonlinearity. We find that the tunneling between the waveguides can
be suppressed in a wide range of parameters due to nonlinearity. Such
suppression of tunneling is different from the coherent destruction of
tunneling in a linear medium, which occurs only at the isolated degeneracy
point of the quasienergies. We call this novel suppression nonlinear coherent
destruction of tunneling.Comment: 4 pages,5 figure
Quasi-energies and Floquet states of two weakly coupled Bose-Einstein condensates under periodic driving
We investigate the quasi-energies and Floquet states of two weakly coupled
Bose-Einstein condensates driven by a periodic force. The quasi-energies and
Floquet states of this system are computed within two different theoretical
frameworks: the mean-field model and the second-quantized model. The mean-field
approach reveals a triangular structure in the quasi-energy band. Our analysis
of the corresponding Floquet states shows that this triangle signals the onset
of a localization phenomenon, which can be regarded as a generalization of the
well-known phenomenon called coherent destruction of tunneling. With the second
quantized model, we find also a triangular structure in the quantum
quasi-energy band, which is enveloped by the mean-field triangle. The close
relation between these two sets of quasi-energies is further explored by a
semi-classical method. With a Sommerfeld rule generalized to time-dependent
systems, the quantum quasi-energies are computed by quantizing semiclassically
the mean-field model and they are found to agree very well with the results
obtained directly with the second-quantized model.Comment: 8pages,12figure