Nonlinear Magneto-optics and Reduced Group Velocity of Light in Atomic Vapor with Slow Ground State Relaxation

A Stern–Gerlach experiment for slow light

“…Slow light experiments directly illustrate the highly dispersive nature of electromagnetically induced transparency [2][3][4] . More recently, a stopping of light was also demonstrated 9,10 .…”

Slow-light pulses in moving media

“…The group velocity v g has been demonstrated [1][2][3][4][5] to be as low as a few meters per second. The specific mechanism to slow down light to such an impressive degree is not relevant for the analysis presented here.…”

“…On the other hand, the pulse will bounce back when, paradoxically, the flow slows down. This effect is sensitive to minute changes in flow speed and can be applied in precision measurements of flows with the present state of the art in slowing down light [1][2][3][4][5].…”

“…Slow light can be generated using Electromagnetically-Induced Transparency [8,9] or exploiting light-atom amplification in Bose-Einstein condensates [5]. Typically [1][2][3][4][5], the steep linear slope (2) of the susceptibility is only valid within a narrow frequency window…”

“…Consequently, a wave packet moving against the current will never enter a region where the flow is faster than the wave velocity in the medium. So, if we send in a pulse of slow light [1][2][3][4][5] to move against the flow we would expect the pulse to freeze or to run backwards [6] when the speed of the medium exceeds the group velocity v g . Yet exactly the opposite happens.…”