Optically Inhibited Collisional Dephasing

Abstract

We have performed a photon-echo experiment on the 555.6-nm intercombination line of atomic Yb vapor which demonstrates that an intense laser field acts to inhibit the dephasing resulting from velocity-changing collisions. This finding implies that the optical Bloch equations, which assume that relaxation is independent of the strength of the driving field, cannot correctly describe the behavior of gas-phase samples in all regimes.

Line “narrowing” in strong optical fields

“…3 and 4 show the dependence of the normalized pure dephasing rate T Ã 2 ð0Þ=T Ã 2 ðOÞ as a function of the Rabi frequency for different parameters of the PLV. As expected from inequalities (8), deviation of T Ã 2 ðOÞ from T Ã 2 ð0Þ becomes substantial at OXK: But if D > K; contrary to the expectations based on the previously published results [8][9][10][11] the dephasing rate first surprisingly increases (see Fig. 3).…”

“…Generally, first experimental observation of dephasing under condition O > t c in optical domain was reported twenty years ago [8] for the system Pr 3þ :LaF 3 : Later the influence of strong optical fields on dephasing process was studied for collision induced broadening in a gas [9] and in a ruby crystal [10]. In all papers strong deviations from the Bloch equations were reported with a qualitative conclusion that T 2 approaches 2T 1 when the optical field increases.…”

Adiabatic passage with spin locking in Tm3+:YAG

“…Many NMR techniques have been dwelling on this spinlocking feature [14], starting with the well known double nuclear resonance [15]. Similar locking of electronic dipoles has been observed at optical frequency, both in * electronic mail: jean-louis.legouet@lac.u-psud.fr solids [16,17] and gases [18][19][20].…”

On the relaxation of a two-level system driven by a strong electromagnetic field

“…A similar failure of the SBE was subsequently demonstrated by photon echo experiments on Yb vapor. 24 These experiments stimulated researchers to consider generalizations to the standard optical Bloch equations. [25][26][27][28][29][30][31][32][33][34][35][36] In this paper it will be shown that many of these treatments correspond to a certain limit of the GBE.…”