Hannover 2013 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

Q: Fachverband Quantenoptik und Photonik

Q 3: Quantum gases: Interaction effects I

Q 3.5: Vortrag

Montag, 18. März 2013, 12:15–12:30, E 001

Bifurcations and exceptional points in dipolar Bose-Einstein condensates — •Robin Gutöhrlein, Jörg Main, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Deutschland

Bose-Einstein condensates are described in a mean-field approach by the nonlinear Gross-Pitaevskii equation and exhibit phenomena of nonlinear dynamics. The eigenstates can undergo bifurcations in such a way that two or more eigenvalues and the corresponding wave functions coalesce at critical values of external parameters, e.g. the scattering length. At the critical point the coalescing states show the properties of an exceptional point. We present a method to uncover all states participating in a pitchfork bifurcation, and investigate in detail the signatures of exceptional points related to bifurcations in dipolar condensates. For the perturbation by two parameters, viz. the scattering length and a parameter breaking the symmetry of the trap, two cases leading to different characteristic eigenvalue and eigenvector patterns under cyclic variation of the parameters need to be distinguished. The observed structures resemble those obtained by G. Demange and E.-M. Graefe [J. Phys. A, 45:025303, 2012] using perturbation theory for non-Hermitian operators in a linear model. Furthermore, the splitting of the exceptional point under symmetry breaking in either two or three branching singularities is examined. Characteristic features are observed when multiple exceptional points are simultaneously encircled.