Collisional decoherence during writing and reading quantum states

Collisions, even though they do not limit the lifetime of quantum information stored in ground-state hyperfine coherences, may severely limit the fidelity for quantum memory when they happen during the write and read process. This imposes restrictions on the implementation of Raman-type quantum processes in thermal vapor cells and their performance as a quantum memory. We study the effect of these collisions in our experiment.