Spin coherence in semiconductor quantum dots

Femtosecond-resolved Faraday rotation is used to probe spin dynamics in chemically synthesized CdSe quantum dots 22-80 Angstrom in diameter from T=6-282 K. The precession of optically injected spins in a transverse magnetic field indicates that the measured relaxation lifetime of the spin polarization is dominated by inhomogeneous dephasing, ranging from similar to 3 ns at zero field to <100 ps at 4 T. Fourier analysis reveals a multiperiodic Larmor precession, with several distinct g factors ranging from similar to 1.1 to 1.7. [S0163-1829(99)51316-7].