Tilted-field exciton beats in a quantum well

Quantum beats generated by a linearly polarised pump pulse have been used to reveal the spin structure of the n=1 heavy-hole exciton transition in a GaAs/AlGaAs quantum well in magnetic field applied obliquely to the growth axis. Pump-induced rotation of the plane of polarisation of a delayed probe pulse reflected from the sample shows a complex superimposed beat pattern. Fitting the eigenvalues of the exciton spin Hamiltonian to the extracted beat frequencies gives high-precision values for the electron and hole g-factors and exchange interactions.