Polarization transfer from photon to electron spin in g factor engineered quantum wells

The authors demonstrate polarization transfer from a photon to an electron spin intermediated by a light-hole exciton in a GaAs∕AlGaAs quantum well, which has an engineered electron g factor of less than 0.01 for an in-plane magnetic field. Negative spin polarization was clearly observed at the selective excitation of the light-hole exciton from two-color time-resolved Kerr rotation. This demonstration is a necessary step towards demonstrating coherence transfer from a photon to an electron spin, which is necessary for building a quantum repeater used for long distance quantum communications.