The dynamics of quantum states of light propagating through slow-light media have been well- characterized both theoretically and experimentally. The question as to how quantum properties like entanglement behave upon propagation through a gain-assisted fast-light medium, however, has not previously been investigated. Additionally, theoretical modeling of inverted atomic ensembles acting as fast-light media has resulted in a controversy as to whether detecting any advance of a few-photon state would be possible in the presence of noise added by spontaneous emission. Here we investigate this regime by sending one half of a bipartite entangled state of two-mode squeezed vacuum through a fast-light medium of Rb vapor. We show that the quantum correlations associated with continuous-variable entanglement can be advanced by small amounts relative to the time scale of the correlations between the modes while maintaining the entanglement. Our results shed some light on the low photon number controversy and provide an original approach to observing the role of quantum noise in limiting the propagation of quantum information under conditions of anomalous dispersion.
entanglement, fast light, quantum information