Microwave power-to-frequency transduction via injection pulling of a self-sustained oscillator for Rydberg superheterodyne sensing

A Rydberg superheterodyne sensing architecture is demonstrated in which a self-sustained oscillator (SSO) serves as a dynamically perturbed local oscillator (LO) for microwave detection. The SSO is realized by a phase-controlled radio frequency feedback loop coupled to a transverse electromagnetic cavity containing a Rydberg vapor cell. The system operates near 5.49 GHz using a cesium ladder scheme with an 852 nm probe and a 510 nm coupling laser addressing the 6S1/2–6P3/2–49D3/2 transition, with microwave coupling to the 50P3/2 state. Injection of a microwave signal pulls the SSO frequency via nonlinear dynamics, converting input power into a measurable frequency shift read out optically as a Rydberg probe intermediate-frequency (IF) signal. The response follows Adler-type injection-pulling behavior, with continuous IF tuning with input power. A peak responsivity of ∼35 kHz/dB is observed, with enhanced power-to-frequency responsivity near synchronization. These results demonstrate power-to-frequency transduction using a dynamically perturbed LO combined with Rydberg atomic readout.