Optically Induced Coherent Spin Transients in an Atomic Ground State

J. Mlynek, Stefan Burschka, Egbert Buhr

Stefan Burschka, J. Mlynek

Hui‐jun Li, Chao Hang, Guoxiang Huang

Martin Rosatzin, Dieter Suter, Wulfhard K. Lange +1 more

We report detailed studies of freely evolving Zeeman coherence (Zeeman quantum beats) observed after optically pumping a gas of Na atoms and suddenly turning off the light field. This Zeeman coherence corresponds to a macroscopic magnetization that precesses in an external magnetic field; it is detected with a cw optical probe beam by using polarization-selective detection of the transmitted light. The amplitude and the phase of the signal show a pronounced variation with laser intensity, laser detuning, and the strength of the magnetic field. This dependence was measured on the 3s2S1/2 ground state of sodium, using the D1 line for optical excitation and detection. The experimental data are compared with theoretical predictions based on a Bloch-type equation of motion for an optically driven spin system in a J = 1/2 ground state.

K. Wódkiewicz

Mark C. Phillips, Hailin Wang

We report experimental studies of electromagnetically induced transparency (EIT) arising from exciton spin coherence in the transient optical response of GaAs quantum wells. The exciton spin coherence, which is a direct result of Coulomb correlations between excitons with opposite spins, is induced via bound or unbound two-exciton states. Theoretical analyses based on a three-level model illustrate the manifestation of EIT in a transient regime and provide qualitative guidance for understanding the transient behaviors observed in the EIT experiments. Additional studies of the effects of exciton energy renormalization on optical Stark splitting also provide insights on how exciton many-body interactions can lead to unusual time-dependent asymmetric EIT line shapes.