Producing slow light in warm alkali vapor using electromagnetically induced transparency

Abstract

We present undergraduate-friendly instructions on how to produce light pulses propagating through warm Rubidium vapor with speeds less than 400 m/s, i.e., nearly a million times slower than c. We elucidate the role played by electromagnetically induced transparency (EIT) in producing slow light pulses, and discuss how to achieve the required experimental conditions. Various EIT linewidth broadening mechanisms are described. The optical set up is presented, and details provided for preparation of pump, probe, and reference pulses of required size, intensity, temporal width, and polarization purity. We discuss in detail how to adequately magnetically shield the alkali vapor sample. Our instructions include drawings for parts and information on prices and vendors. In the spirit of presenting a stand-alone article for producing slow light, we provide in Supplementary Notes, a detailed semiclassical derivation of EIT and slow light that should be amenable to advanced undergraduates, and details of an auxiliary measurement to ensure the suppression of residual stray magnetic fields below 0.2 milliGauss over the entire laser-atom interaction region.