Generation of pulses with negative group velocities via four-wave mixing in 85 Rb

Ryan T. Glasser, Paul D. Lett, Ulrich Vogl

We generate pairs of superluminal pulses via four-wave mixing. A relative pulse peak advancement of the seed pulses of > 50% is demonstrated. Generated conjugate pulses can propagate with negative group velocities of up to v g = − 1 880 c.

Takashi Nakajima

Ryan T. Glasser, Ulrich Vogl, Paul D. Lett

We report on the four-wave mixing of superluminal pulses, in which both the injected and generated pulses involved in the process propagate with negative group velocities. Generated pulses with negative group velocities of up to v(g)=-1/880c are demonstrated, corresponding to the generated pulse's peak exiting the 1.7 cm long medium ≈50 ns earlier than if it had propagated at the speed of light in vacuum, c. We also show that in some cases the seeded pulse may propagate with a group velocity larger than c, and that the generated conjugate pulse peak may exit the medium even earlier than the amplified seed pulse peak. We can control the group velocities of the two pulses by changing the seed detuning and the input seed power.

A. A. Zobolotskii

B. Macke, B. S�gard

Ulrich Vogl, Ryan T. Glasser, Paul D. Lett

We generate superluminal pulses via four-wave-mixing in 85Rb vapor and imprint images on the pulses. This allows us to resolve experimentally the arrival time of the spatial information imprinted on the pulses.