Figure 2: Optical pumping of a single spin.
From: Macroscopic rotation of photon polarization induced by a single spin
(In all panels, symbols are used for experimental measurements and solid lines for numerical simulations). (a,b) Reflectivity spectra centred on the QD-induced peak, for various values of the incident power P0, using linear (X) and circular (L) polarization, respectively. In both cases, a decrease of the peak amplitude is observed. The reflectivity spectra have been vertically shifted for clarity. (c) QD-induced reflectivity variations ΔRQD measured for circularly and linearly polarized excitation, as a function of the incident power (bottom axis) and of the corresponding intracavity photon number n (top axis)25. (d) Four-level system and principle of hole spin pumping using a circularly polarized pump (ascending red arrow, resonant excitation with a left-handed (L) circularly polarized pump beam; black descending arrows, spontaneous emission of either L- or R-polarized photons; horizontal grey arrows, spin-flip processes).
