A Large Atom Number Metastable Helium Bose-Einstein Condensate

TL;DR

This paper reports the creation of a large Bose-Einstein condensate of metastable helium with over 15 million atoms, achieved through improved cooling techniques, enabling advanced detection methods and extending to fermionic isotopes.

Contribution

The authors demonstrate a significant increase in atom number in helium BECs using one-dimensional Doppler cooling, and successfully apply this method to fermionic helium isotopes.

Findings

Achieved over 1.5x10^7 atoms in helium BEC, a 25-fold increase.

Applied Doppler cooling inside magnetic traps for improved condensate production.

Developed multiple detection techniques for monitoring condensate formation and decay.

Abstract

We have produced a Bose-Einstein condensate of metastable helium (4He*) containing over 1.5x10^7 atoms, which is a factor of 25 higher than previously achieved. The improved starting conditions for evaporative cooling are obtained by applying one-dimensional Doppler cooling inside a magnetic trap. The same technique is successfully used to cool the spin-polarized fermionic isotope (3He*), for which thermalizing collisions are highly suppressed. Our detection techniques include absorption imaging, time-of-flight measurements on a microchannel plate detector and ion counting to monitor the formation and decay of the condensate.