Coherence length calculation for the outcoupled beam of atom laser

Abstract

We use the theory of coupled Gross-Pitaevskii equations to derive an expression for the current density of the propagating atoms coupled out of the condensate under the influence of gravity. By describing the propagation vector of the atoms and using a theoretical definition of the coherence length, we calculate the coherence lengths of 37 K, 141 Ce, and 249 Fm atom lasers numerically. Our calculation method is verified with the available experimental and theoretical data in the literature. The results showed a very good agreement.

The Effect of the Depopulation Rate Parameters on the Remaining Atoms in the Bose-Einstein Condensation

“…Immediately when the output coupling 𝑟𝑓-field is switched on at 𝑡 = 0, the whole condensate undergoes an initial rapid oscillations damping through all the coupled states due to the escape of the untrapped atoms out of the trap under the influence of gravity. At the same time, other atoms move to the resonance point replacing the leaving atoms, until a quasi-stationary state is reached [15]. In this stage, the number of atoms remaining in the condensate is studied depending on the effect of the depopulation rate parameters in 1D(z direction).…”