Figure 3: Macroscopic Kerr rotation induced by a single spin in a cavity-QED device.
From: Macroscopic rotation of photon polarization induced by a single spin
(a) Polarization states for the incident and reflected beam. The reflected beam results from the interference of two contributions: direct reflection and light injected into and re-extracted from the cavity. (b) Simplified scheme of the experimental setup used for spin optical pumping and Kerr rotation measurements on a QD-pillar cavity device. The polarization states are indicated: the probe beam (blue arrows) is linearly polarized, whereas the pump beam (black arrows) is either left-handed (L-pump) or right-handed (R-pump) circularly polarized. EOM, electro-optical modulator allowing the lock-in detection setup to filter out the contribution from the unmodulated pump beam. PBS, polarizing beam splitter, separating the horizontal (H) and vertical (V) components of the beam polarization, allowing the measurement of the Kerr rotation angle. (c) Kerr rotation angle as a function of ωprobe, with ωpump fixed at 1.345857, eV. Symbols: experimental data (L-pump in red, R-pump in green): macroscopic Kerr rotation angles up to +6° or −6° are obtained, depending on the pump polarization handedness. Solid line: theoretical fit with partial spin initialization. Dashed line: theoretical prediction with perfect spin initialization. (d) Kerr rotation angle as a function of ωpump, with ωprobe fixed at a maximum of Kerr rotation (thick vertical arrow in c).
