Macroscopic Quantum Fluctuations in the Josephson Dynamics of Two Weakly Linked Bose-Einstein Condensates

We study the quantum corrections to the Gross-Pitaevskii equation for two weakly linked Bose-Einstein condensates. The goals are: 1) to investigate dynamical regimes at the borderline between the classical and quantum behaviour of the bosonic field; 2) to search for new macroscopic quantum coherence phenomena not observable with other superfluid/superconducting systems. Quantum fluctuations renormalize the classical Josephson oscillation frequencies. Large amplitude phase oscillations are modulated, exhibiting collapses and revivals. We describe a new inter-well oscillation mode, with a vanishing (ensemble averaged) mean value of the observables, but with oscillating mean square fluctuations. Increasing the number of condensate atoms, we recover the classical Gross-Pitaevskii (Josephson) dynamics, without invoking the symmetry-breaking of the Gauge invariance.Comment: Submitte

Vector Gauge Theory

Gauge fields arise naturally in theories of free fermions when basis vectors are associated with the fermions and are allowed to vary with the spacetime point. A single three-component complex unit vector gives rise to the electromagnetic field, and two orthonormal five-component complex vectors result in U(2). 1

Construction of a pseudo-binaryphasediagram for multi-componentNi-base superalloys

A novel method for the representation of multi-component thermodynamics through a pseudo-binary system without any major assumption is presented. Pseudobinary phasediagrams have been constructed for three representative Ni-basesuperalloys. Expressions for the Gibbs energy of the different phases as a function of the pseudo-binary composition and temperature have been derived. The information derived from the pseudo-binaryphasediagrams and Gibbs energy of the various phases represented through pseudo-binary compositions is applied to (a) solidification calculations for determination of dendrite arm spacing using cellular automata model and (b) phase field calculations