Optimization of evaporative cooling towards a large number of Bose-Einstein condensed atoms

TL;DR

This paper uses quantum kinetic theory to optimize evaporative cooling of trapped bosonic atoms, significantly increasing the number of Bose-Einstein condensed atoms by refining the cooling trajectory.

Contribution

It introduces an optimized cooling strategy based on quantum kinetic theory that enhances condensate size and efficiency compared to conventional methods.

Findings

Over two orders of magnitude increase in condensed atoms.

Acceleration of cooling near the BEC transition point is highly effective.

A combined exponential and linear frequency sweep improves cooling efficiency.

Abstract

We study the optimization of evaporative cooling in trapped bosonic atoms on the basis of quantum kinetic theory of a Bose gas. The optimized cooling trajectory for $^{87}$Rb atoms indicates that the acceleration of evaporative cooling around the transition point of Bose-Einstein condensation is very effective against loss of trapped atoms caused by three-body recombination. The number of condensed atoms is largely enhanced by the optimization, more than two orders of magnitude in our present calculation using relevant experimental parameters, as compared with the typical value given by the conventional evaporative cooling where the frequency of radio-frequency magnetic field is swept exponentially. In addition to this optimized cooling, it is also shown that highly efficient evaporative cooling can be achieved by an initial exponential and then a rapid linear sweep of frequency.