Rydberg-State Engineering: Investigations of Tuning Schemes for Continuous Frequency Sensing

On-resonance Rydberg atom-based radio-frequency-(rf) electric-field sensing methods remain limited by the narrow frequency-signal detection bands available from resonant transitions. An additional rf tuner field can be used to dress or shift a target Rydberg state to return a detuned signal field to resonance and thus dramatically extend the frequency range available for resonant sensing. Here we investigate three distinct tuning-level schemes based on adjacent Rydberg transitions, which are shown to have distinct characteristics and can be controlled with the frequency or the strength of the tuning field. We further show that a two-photon Raman peak can be used as an effective tuning feature separate from conventional Autler-Townes splitting. We compare our tuning schemes with ac Stark effect-based broadband rf-field sensing and show that although the sensitivity is diminished with tuning away from a resonant state, it nevertheless can be used in configurations where there is a low density of Rydberg states, which would result in a weak ac Stark effect.