Steering between outputs of a beamsplitter using Gaussian states of light with excess noise

We have studied the conditions for quantum steering between output modes when squeezed Gaussian light and vacuum mix in a beamsplitter as a function of the amount of squeezing and purity of the incident state. For Gaussian measurements, we find that for sufficiently strong squeezing, steering is possible regardless of the purity of the incident state. Two different types of non-Gaussian measurements were also considered. For one of them, an increase with respect to Gaussian measurements of the set of two-way-steerable states is obtained only for unbalanced beamsplitters.Comment: 8 pages, 9 figure

Chaos induced coherence in two independent food chains

Coherence evolution of two food web models can be obtained under the stirring effect of chaotic advection. Each food web model sustains a three--level trophic system composed of interacting predators, consumers and vegetation. These populations compete for a common limiting resource in open flows with chaotic advection dynamics. Here we show that two species (the top--predators) of different colonies chaotically advected by a jet--like flow can synchronize their evolution even without migration interaction. The evolution is charaterized as a phase synchronization. The phase differences (determined through the Hilbert transform) of the variables representing those species show a coherent evolution.Comment: 5 pages, 5 eps figures. Accepted for publication in Phys. Rev.