A Concept for Laser Cooling of Carbon Dimers

While carbon plays an ubiquitous role in physics, chemistry, engineering, biology, and medicine, methods to achieve quantum control over carbon are not as developed as for other species. Direct laser cooling of atomic carbon is hard as the relevant transitions are located in the VUV. Here, we present a concept for laser cooling of ¹²C dimers. C₂ has a relatively simple level scheme due to its large vibrational spacings, vanishing nuclear spin, and weak spin orbit coupling that minimizes singlet-triplet mixing. C₂ offers several potential transition bands for laser cooling in accessible wavelength ranges. We discuss the characteristics of these bands, their suitability for laser cooling, and technical implications for laser cooling schemes. We find that laser cooling of C₂ is within reach, requiring a technical complexity comparable to existing laser cooling setups for molecules.