Optical pumping of TeH⁺: Implications for the search for varying m_p/m_e

Molecular overtone transitions provide optical frequency transitions sensitive to variation in the proton-to-electron mass ratio (m = m_p/m_e). However, robust molecular state preparation presents a challenge critical for achieving high precision. Here, we characterize infrared and optical-frequency broadband laser cooling schemes for TeH⁺, a species with multiple electronic transitions amenable to sustained laser control. Using rate equations to simulate laser cooling population dynamics, we estimate the fractional sensitivity to m attainable using TeH⁺. We find that laser cooling of TeH⁺ can lead to significant improvements on current m variation limits.