Suppression of collision-induced dephasing by periodic, erratic, or noisy driving

We compare different driving scenarios for controlling the loss of single particle coherence of an initially coherent preparation in the vicinity of the hyperbolic instability of the two-mode bose-Hubbard model. In particular we contrast the quantum Zeno suppression of decoherence by broad-band erratic or noisy driving, with the Kapitza effect obtained for high frequency periodic monochromatic driving.Comment: 6 pages, 3 figure

Interaction-induced dynamical phase locking of Bose-Einstein condensates

We show that interactions result in the emergence of a {\it definite} relative-phase between two initially incoherent Bose-Einstein condensates. The many-realization interference fringe visibility is universal at $g_{12}^{(1)}\sim1/3$ throughout the Josephson interaction regime, as evident from a semiclassical picture. Other types of incoherent preparation yield qualitatively different coherence dynamics.Comment: 4 pages, 5 figure