Modeling Quantum Beats by Degenerate Four‐Wave Mixing Spectroscopy in a Single GaAs/AlGaAs Quantum Ring

It has been proposed theoretically that quantum beat spectroscopy provides a direct experimental evidence of the fine states of quantized ring orbital angular momentum in a quantum ring. When a pair of picosecond pulses excites the fine exciton states coherently, oscillations can be observed in time‐integrated degenerate four‐wave mixing signals for increasing delay time. It has been found that the oscillation periods are dominated by energy separations of the fine levels near the central energy of laser spectrum due to strong coherent coupling. Magnetic dependence of the fine level separation is also investigated in terms of signal intensity and quantum beat periods.