Optically trapped Feshbach molecules of fermionic Dy 161 and K 40 : Role of light-induced and collisional losses

We study the decay of a dense, ultracold sample of weakly bound DyK dimers stored in an optical dipole trap. Our bosonic dimers are composed of the fermionic isotopes <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mmultiscripts> <a:mi>Dy</a:mi> <a:mprescripts/> <a:none/> <a:mn>161</a:mn> </a:mmultiscripts> </a:math> and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mmultiscripts> <b:mi mathvariant="normal">K</b:mi> <b:mprescripts/> <b:none/> <b:mn>40</b:mn> </b:mmultiscripts> </b:math> , which is of particular interest for experiments related to pairing and superfluidity in fermionic systems with mass imbalance. We have realized dipole traps with near-infrared laser light in four different wavelength regions between 1050 and 2002 <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mi>nm</d:mi> </d:math> . We have identified trap-light-induced processes as the overall dominant source of losses, except for wavelengths around 2000 <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mi>nm</e:mi> </e:math> , where light-induced losses appeared to be much weaker. In a trap near 1550 <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mi>nm</f:mi> </f:math> , we found a plateau of minimal light-induced losses, and by carefully tuning the wavelength we reached conditions where losses from inelastic collisions between the trapped dimers became observable. For very weakly bound dimers close to the center of a magnetically tuned Feshbach resonance, we demonstrate the Pauli suppression of collisional losses by about an order of magnitude.