Large negative and positive delay of optical pulses in coherently prepared dense Rb vapor with buffer gas

2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91832We experimentally study the group time delay for a light pulse propagating through hot Rb vapor in the presence of a strong coupling field in a $Λ$ configuration. We demonstrate that the ultra-slow pulse propagation is transformed into superluminal propagation as the one-photon detuning of the light increases due to the change in the transmission resonance lineshape. Negative group velocity as low as -c/10^6=-80 m/s is recorded. We also find that the advance time in the regime of the superluminal propagation grows linearly with increasing laser field power.5 pages, 6 figuresQuantum PhysicsLarge negative and positive delay of optical pulses in coherently prepared dense Rb vapor with buffer gastext