Prospects for Narrow-line Cooling of KRb Molecules in Rovibrational Ground State

Abstract

We propose and experimentally investigate a scheme for narrow-line cooling of KRb molecules in the rovibrational ground state. We show that the spin-forbidden ${\mathrm{X}}^1{\mathrm{\Sigma }}^{+}\to {\mathrm{b}}^3{\mathrm{\Pi }}_{0^{+}}$ transition of KRb is ideal for realizing narrow-line laser cooling of molecules because it has highly diagonal Franck-Condon factors and narrow linewidth. In order to confirm the prediction, we performed the optical and microwave spectroscopy of ultracold ${}^{41}$K${}^{87}$Rb molecules, and determined the linewidth ($2\pi \times$ 4.9(4) kHz) and Franck-Condon factors for the ${\mathrm{X}}^1{\mathrm{\Sigma }}^{+}(v^{\prime \prime }=0)\to {\mathrm{b}}^3{\mathrm{\Pi }}_{0^{+}}(v^{\prime }=0)$ transition (0.9474(1)). This result opens the door towards all-optical production of polar molecules at sub-microkelvin temperatures.

4 pages, 5 figures

References in corpus (3)

• A High Phase-Space-Density Gas of Polar Molecules
• The hyperfine energy levels of alkali metal dimers: ground-state polar molecules in electric and magnetic fields
• The coupling of the X${}^1{\Sigma }^{+}$ and a${}^3{\Sigma }^{+}$ states of KRb

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• Tune-out and magic wavelengths for ground-state ${}^{23}$Na${}^{40}$K molecules
• Production of ultracold ground state LiRb molecules by photoassociation through a resonantly coupled state
• Floquet Engineering Ultracold Polar Molecules to Simulate Topological Insulators
• Model for the hyperfine structure of electronically-excited $\mathrm{KCs}$ molecules
• Cavity probe for real-time detection of atom dynamics in an optical lattice
• Nondestructive dispersive imaging of rotationally excited ultracold molecules
• Characterization of the lowest excited-state ro-vibrational level of ${}^{23}$Na${}^{87}$Rb
• The $C{}^1{\Sigma }^{+}$, $A{}^1{\Sigma }^{+}$, and $b{}^3{\Pi }_{0^{+}}$ states of LiRb
• Narrowline Laser Cooling and Spectroscopy of Molecules via Stark States