Slow-light media are of interest in the context of quantum computing and enhanced measurement of quantum effects, with particular emphasis on using slow light with single photons. We use light-in-flight imaging with a single-photon avalanche diode camera array to image in situ pulse propagation through a slow-light medium consisting of heated rubidium vapor. Light-in-flight imaging of slow-light propagation enables direct visualization of a series of physical effects, including simultaneous observation of spatial pulse compression and temporal pulse dispersion. Additionally, the single-photon nature of the camera allows for observation of the group velocity of single photons with measured single-photon fractional delays greater than 1 over 1 cm of propagation.
American Physical Society