We perform magnetically-assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed P (N = 1) branch of either theX 2 Σ + (000) ↔Ã 2 Π 1/2 (000) or theX 2 Σ + (000) ↔B 2 Σ + (000) vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through theB (000) state for both the (100) level of the Sr-O stretching mode and the 02 0 0 level of the bending mode. The transverse temperature of a SrOH molecular beam is reduced in one dimension by two orders of magnitude to ∼ 700 µK. This approach opens a path towards creating a variety of ultracold polyatomic molecules, including much larger ones, by means of direct laser cooling.Compared to atoms, the additional rotational and vibrational degrees of freedom in molecules give rise to a wide variety of potential and realized scientific applications, including quantum computation [1][2][3], precision measurements [4][5][6][7], and quantum simulation [8,9]. While ultracold diatomic molecules will be extremely valuable in opening novel research frontiers, molecules with three or more atoms have unique capabilities enabled by their significantly more complicated structure [10][11][12][13][14][15][16]. For all molecules to achieve their full scientific potential, they must be cooled. Yet, the desired quantum complexity that molecules provide also leads to challenges for control, detection, and cooling [17]. Assembling ultracold molecules from two laser-cooled atoms has represented one solution and has created ultracold bi-alkali molecules [18][19][20][21][22], including filling of optical lattices with KRb [23]. There are several direct cooling techniques that together routinely cool a much wider variety of molecules into the Kelvin regime [17,24]. Intense research is ongoing to bring these cold molecules into the ultracold regime (< 1 mK). Even though there has been experimental progress on control of polyatomics [25][26][27][28][29][30], optoelectrical cooling of formaldehyde is the only technique that has resulted in a trapped sub-millikelvin sample [31].Cooling of the external motion of neutral atoms from above room temperature into the sub-millikelvin range (leading to, e.g., Bose-Einstein condensation) commonly relies on the use of velocity-dependent optical forces [32]. Laser cooling requires reasonably closed and strong optical electronic transitions, so its use for molecules has been severely limited. Recently, following initial theoretical proposals [33,34] In this Letter, we report the Sisyphus laser cooling of a polyatomic molecule. The dissipative force for compressing phase-space volume is achieved by a combination of spatially varying light shifts and optical pumping into dark sub-levels, which are then remixed by a static magnetic field, as explored previously in atomic systems [45,46]. Since the magnitude of the induced friction force is directly related to the modulation depth of the dressed e...
An experimentally feasible strategy for direct laser cooling of polyatomic molecules with six or more atoms is presented. Our approach relies on the attachment of a metal atom to a complex molecule, where it acts as an active photon cycling site. We describe a laser cooling scheme for alkaline earth monoalkoxide free radicals taking advantage of the phase space compression of a cryogenic buffer-gas beam. Possible applications are presented including laser cooling of chiral molecules and slowing of molecular beams using coherent photon processes.
Ultracold polyatomic molecules have potentially wide-ranging applications in quantum simulation and computation, particle physics, and quantum chemistry. For atoms and small molecules, direct laser cooling has proven to be a powerful tool for quantum science in the ultracold regime. However, the feasibility of laser-cooling larger, nonlinear polyatomic molecules has remained unknown because of their complex structure. We laser-cooled the symmetric top molecule calcium monomethoxide (CaOCH3), reducing the temperature of ~104 molecules from 22 ± 1 millikelvin to 1.8 ± 0.7 millikelvin in one dimension and state-selectively cooling two nuclear spin isomers. These results demonstrate that the use of proper ro-vibronic transitions enables laser cooling of nonlinear molecules, thereby opening a path to efficient cooling of chiral molecules and, eventually, optical tweezer arrays of complex polyatomic species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.