  We propose an all-optical experiment to quantify non-Markovianity in an open
quantum system through quantum coherence of a single quantum bit. We use an
amplitude damping channel implemented by an optical setup with an intense laser
beam simulating a single-photon polarization. The optimization over initial
states required to quantify non-Markovianity is analytically evaluated. The
experimental results are in a very good agreement with the theoretical
predictions.
