CaNH₂ - Cooling Asymmetric Molecules

Laser Cooling: The Force Awakens

Since its invention in the 1980s, laser-cooling technology has evolved into a cornerstone of AMO physics. By enabling the production of ultracold, dense atomic ensembles, researchers have ventured into the realm of quantum degeneracy, and achieved control over individual quantum states using optical tweezers and lattices. These breakthroughs have catalyzed significant advances in quantum computing [1-3], quantum simulation [4-7], atomic clocks [8], and precision tests of fundamental constants [9].

The Ultracold Molecule Chronicles

Building on decades of success in atomic physics, recent research has turned to ultracold molecules as powerful tools for exploring new quantum phenomena. Experimental efforts worldwide, including those in our group, are extending the laser-cooling toolkit into the rich and intricate world of molecules. Over the past decade, laser cooling has been demonstrated in diatomic species (e.g., CaF [20-22], SrF [13], YO [14]), linear triatomic molecules (e.g., CaOH [15], SrOH [16]), and even larger symmetric top molecules (e.g., CaOCH₃ [17]). Yet our ambitions push us further, towards a more complex molecular landscape.

Taming the Untamed: Cooling Asymmetric Molecules

Our latest project, launched in late 2024, takes on a new challenge: adapting established laser-cooling techniques to more complex, asymmetric top molecules. Drawing on theoretical insights from previous studies [19,20], we aim to demonstrate that even large, bent, and twisted molecules can be controlled with laser light. For this experiment, we have chosen CaNH₂—the simplest asymmetric top molecule—to test our cooling strategies and pave the way for broader applications in quantum science.

References

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[15 ]N. B. Vilas, C. Hallas, L. Anderegg, P. Robichaud, A. Winnicki, D. Mitra, and J. M. Doyle, “Magneto-optical trapping and sub-doppler cooling of a polyatomic molecule,” Nature, vol. 606, no. 7912, pp. 70–74, 2022.

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[20] Augenbraun, Doyle, Zelevinsky, and Kozyryev, “Molecular Asymmetry and Optical Cycling: Laser Cooling Asymmetric Top Molecules,” Phys. Rev. X 10, 031022 (2020).