Spectral Broadening of Molecular Transitions Through Dynamic Decoupling with Electric-field Gradients

The extensive energy structure of molecular ions provides a myriad of electric dipole transitions addressable within the RF and microwave spectrum. These narrow linewidth transitions are attractive candidates for robust, laser-free molecular qubits. Electric-field gradients generated from the electrodes of an ion trap introduce an architecture suitable for non-destructive state readout, single qubit and two-qubit gates (PhysRevA. 2021, 104, 042605). Here we discuss a heterodyne detection scheme developed from this architecture to broaden the linewidth of hyperfine parity states within HCl⁺ through dynamic decoupling. Additionally, we demonstrate the application of this scheme for in situ calibration of our qubit control lines using a single trapped atomic species.