Exciton Exchange between Nearly-Free and Acceptor-Bound States of a Positive Trion Assisted by Cyclotron Excitation

In magneto-photoluminescence spectra of a two-dimensional hole gas in a GaAs quantum well we observe coupling of two different radiative states. The pair of coupled states are an acceptor-bound trion AX$\text{}^{+}$ and an essentially free (only weakly localized by a shallow lateral potential) trion X$\text{}^{+}$, brought into resonance by an additional cyclotron excitation controlled by the magnetic field. The coupling mechanism is the exciton transfer, and the optical signature is a clear anticrossing of the emission lines of an X$\text{}^{+}$ and a cyclotron replica of the AX$\text{}^{+}$.