Ultracold Polar Molecules in the Rovibrational Ground State

Abstract

Recently, there has been important progress in the formation of ultracold polar molecules in the rovibrational ground state, thus opening intriguing perspectives for the investigation of strongly correlated quantum systems under the influence of long-range dipolar forces. After an brief introduction into the field of ultracold molecules, we will review our recent experiments on the formation of ultracold LiCs molecules in the absolute ground state X 1 Σ + ,v=0,J=0 via a single photo-association step starting from laser-cooled atoms. 2008 -A hot summer for ultracold moleculesOne of the long-sought goals in the field of cold and ultracold molecules is the creation of a quantum-degenerate gas of ultracold molecules in the absolute internal ground state. A quantum-degenerate gas of groundstate molecules offers intriguing perspectives for high-precision spectroscopic measurement, e.g. on the temporal variation of fundamental constants, for the simulation of non-trivial many-body quantum systems, and for the understanding of molecular reactions close to absolute zero ("ultracold chemistry"). With the tremendous advances in the preparation of ultracold molecules in the vibrational, and even rotational and hyperfine, ground state during the past year, a quantum-degenerate gas of molecules in the absolute ground state has come within reach.

Radio-frequency association of heteronuclear Feshbach molecules

“…Polar molecules have been slowed down and trapped using Stark deceleration in spatially modulated electric fields [5,6,7]. Other approaches are provided by cooling ground state molecules with a buffer gas [8] and by photoassociation in magneto-optical traps, where the lowest vibrational level in ultracold K 2 [9], KRb [10], RbCs [11], Cs 2 [12], and LiCs [13] has been reached. However, these approaches only offer limited state control or temperatures in the mK regime.…”