Optoelectrical cooling of polar molecules

Abstract

We present an opto-electrical cooling scheme for polar molecules based on a Sisyphus-type cooling cycle in suitably tailored electric trapping fields. Dissipation is provided by spontaneous vibrational decay in a closed level scheme found in symmetric-top rotors comprising six low-field-seeking rovibrational states. A generic trap design is presented. Suitable molecules are identified with vibrational decay rates on the order of 100 Hz. A simulation of the cooling process shows that the molecular temperature can be reduced from 1 K to 1 mK in approximately 10 s. The molecules remain electrically trapped during this time, indicating that the ultracold regime can be reached in an experimentally feasible scheme.

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

“…[45][46][47] An optical Stark deceleration scheme utilizing optical dipole forces induced by pulsed fields has also been demonstrated. 48 Rempe's group 49,50 has applied an optoelectrical method for cooling and collecting polar molecules in an electric trap. This approach based on Sisyphus cooling was recently demonstrated for the CH 3 F 50 and formaldehyde (H 2 CO) 51 molecules and it holds great promise for precision spectroscopy and collisional studies of cold and ultracold polar molecules.…”

Deceleration of supersonic beams using inhomogeneous electric and magnetic fields

“…These three related methods offer considerable flexibility in the manipulation of the translational motion of a wide range of molecules, and first real applications in high-resolution spectroscopy and reaction dynamics are becoming possible. At present, the phase-space densities that can be reached are not sufficient for considering further cooling steps, but in future the implementation of continuous trap loading and optical cooling schemes [32][33][34][165][166][167][168][169][170] in combination with deceleration techniques appears promising.…”

Cavity sideband cooling of trapped molecules

“…Even a three-dimensional (3D) scheme has been proposed resembling the popular magneto-optical trap for atoms [5]. Zeppenfeld et al have proposed to use electro-optical forces to carry away up to 1 K per spontaneously decaying infrared (IR) photon [6]. Optical cavities have been predicted [7,8] and used for atoms [9] as a way to achieve translational cooling without relying on spontaneous emission, in principle allowing cooling of molecules.…”