High-contrast double Bragg interferometry via detuning control

We propose high-contrast Mach-Zehnder atom interferometers based on double Bragg diffraction (DBD) operating under external acceleration. To mitigate differential Doppler shifts and experimental imperfections, we introduce a tri-frequency laser scheme with dynamic detuning control. We evaluate four detuning-control strategies—conventional DBD, constant detuning, linear detuning sweep (DS-DBD), and a hybrid protocol combining detuning sweep with optimal control theory (OCT)—using exact numerical simulations and a five-level S-matrix model. The OCT strategy provides the highest robustness, maintaining contrast above 95\% under realistic conditions, while the DS-DBD strategy sustains contrast above 90\% for well-collimated Bose-Einstein condensates. These results offer practical pathways to enhancing DBD-based interferometers for precision quantum sensing and fundamental physics tests.