Quantum Theory of Spin Dynamics of Exciton-Polaritons in Microcavities

We present the quantum theory of momentum and spin relaxation of exciton-polaritons in microcavities. We show that giant longitudinal-transverse splitting of the polaritons mixes their spin states, which results in beats between right- and left-circularly polarized photoluminescence of microcavities, as was recently experimentally observed [M. D. Martin et al., Phys. Rev. Lett. 89, 077402 (2002)]. This effect is strongly sensitive to the bosonic stimulation of polariton scattering.

Figure 1

A Poincaré sphere with a pseudospin. The equator of the sphere corresponds to different linear polarizations, while the poles correspond to two circular polarizations.

Figure 2

Longitudinal-transverse (TM-TE) polariton splitting calculated for a microcavity sample from Ref. 6 for the lower polariton branch (LPB) and the upper polariton branch (UPB) for different detunings.

Figure 3

Polarization degree of the photoluminescence at different angles (0°, 14°, and 20°) from the model CdTe microcavity at zero detuning, calculated using Eqs. (15, 16, 17) for a pulsed nonresonant excitation with the excitation power of $7\mu \mathrm{J}$ per pulse (a)–(c) and excitation power of $700\mu \mathrm{J}$ per pulse (d)–(f). The maximum value polariton occupation numbers achieved at the given angles are indicated on the figures.

Figure 4

The same as Fig. 3, but for the negative detuning of $-10\mathrm{m}\mathrm{e}\mathrm{V}$.