Dynamically Enhanced Two-Photon Spectroscopy

A novel quantum control protocol utilizing two-photon processes with trigonometric pulse modulation is developed, enabling the intermediate state population's dynamic elimination (DE). The proposed DE technique excels at single-photon resonance in contrast to the well-known adiabatic elimination (AE) regime, which requires large single-photon detuning and strong pulses. The DE approach outperforms AE in efficiency and exhibits enhanced resilience to one-photon detuning since the key control parameter, the effective two-photon Rabi frequency, inversely proportional to the modulation frequency, does not depend on the one-photon detuning. The comprehensive analysis of population transfer and Ramsey interferometry demonstrates the protocol's superiority, achieving enhanced signal-to-noise ratios and higher fidelities with respect to existing two-photon methods.