A quantum study of slow light via electromagnetically induced transparency - Magnus Hsu

Using electromagnetically induced transparency (EIT), it is possible to delay and store light in atomic ensembles. Theoretical modelling and recent experiments have suggested that the EIT storage mechanism can be used as a memory for quantum information. We present experiments that quantify the noise performance of an EIT system for conjugate amplitude and phase quadratures. It is shown that our EIT system adds excess noise to the delayed light that has not hitherto been predicted by published conventional theoretical modelling. In analogy with other continuous-variable quantum information systems, the performance of our EIT system is characterised in terms of conditional variance and signal transfer.