12,478 research outputs found
Non Singular Origin of the Universe and the Cosmological Constant Problem (CCP)
We consider a non singular origin for the Universe starting from an Einstein
static Universe in the framework of a theory which uses two volume elements
and , where is a metric independent
density, also curvature, curvature square terms, first order formalism and for
scale invariance a dilaton field are considered in the action. In the
Einstein frame we also add a cosmological term that parametrizes the zero point
fluctuations. The resulting effective potential for the dilaton contains two
flat regions, for relevant for the non singular
origin of the Universe and , describing our present
Universe. Surprisingly, avoidance of singularities and stability as imply a positive but small vacuum energy as . Zero vacuum energy density for the present universe is
the "threshold" for universe creation.Comment: awarded an honorable mention in the Gravity Research Foundation 2011
Awards for Essays in Gravitation for 201
Frictionless quantum quenches in ultracold gases: a quantum dynamical microscope
In this article, a method is proposed to spatially scale up a trapped
ultracold gas while conserving the quantum correlations of the initial
many-body state. For systems supporting self-similar dynamics, this is achieved
by implementing a many-body finite-time frictionless quantum quench of the
harmonic trap which acts as a quantum dynamical microscope.Comment: 5 pages, 3 figure
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