Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 24: Quanteninformation: Repeater und Speicher
Q 24.5: Talk
Tuesday, March 13, 2012, 11:45–12:00, V7.02
Electromagnetically induced transparency (EIT) in a realistic atomic quantum memory for light — •Oxana Mishina1, Michael Scherman1, Pietro Lombardi1,3, Alberto Bramati1, Alexandra Sheremet2, Dmitriy Kupriyanov2, Julien Laurat1, and Elisabeth Giacobino1 — 1Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure and CNRS, Paris, France — 2Department of Theoretical Physics, State Polytechnic University, St.-Petersburg, Russia — 3European Laboratory for Non-Linear Spectroscopy, University of Florence, Sesto-Fiorentino (Firenze), Italia
In this work we identify a process detrimental for the EIT based quantum memory in alkali gases. Our main tool is a theoretical model we developed for the EIT in a Lambda scheme with more than one excited level. Such a multiple Lambda-type interaction arises due to the hyperfine splitting typical for the alkali atoms and rare earth ions currently used for quantum memory experiments. Using this model we show that the presence of extra excited states may strongly damage the EIT if inhomogeneous broadening is comparable with the excited level spacing. We also proposed a method to enhance the EIT in an alkali vapor and successfully demonstrated it experimentally showing a good agreement with theoretical predictions. Furthermore we apply our theory to optimize a quantum memory performance in a cold atomic cloud. We believe our theory captures the general phenomena ruling the efficiency of EIT based quantum memories and it could be adapted to improve the performance of other EIT based systems.