Direct evaporative cooling of 41K into a Bose-Einstein condensate

TL;DR

This paper demonstrates the first creation of a Bose-Einstein condensate of 41K atoms via direct evaporative cooling, investigates its collisional properties, and observes a Feshbach resonance, highlighting its potential as a coolant.

Contribution

First successful direct evaporative cooling of 41K into a Bose-Einstein condensate and identification of a Feshbach resonance in this isotope.

Findings

Bose-Einstein condensate of 41K was created for the first time.

Upper bound of three-body loss coefficient was determined.

Feshbach resonance observed at 51.42 G in 41K.

Abstract

We have investigated the collisional properties of 41K atoms at ultracold temperature. To show the possibility to use 41K as a coolant, a Bose-Einstein condensate of 41K atoms in the stretched state (F=2, m_F=2) was created for the first time by direct evaporation in a magnetic trap. An upper bound of three body loss coefficient for atoms in the condensate was determined to be 4(2) 10^{-29} cm -6 s-1. A Feshbach resonance in the F=1, m_F=-1 state was observed at 51.42(5) G, which is in good agreement with theoretical prediction.