While the advanced coherent control of qubits is now routinely carried out in low-frequency (gigahertz) systems like single spins, it is far more challenging to achieve for two-level systems in the optical domain. This is because the latter evolve typically in the terahertz range, calling for tools of ultrafast, coherent, nonlinear optics. Using four-wave mixing microspectroscopy, we here measure the optically driven dynamics of a single exciton quantum state confined in a semiconductor quantum dot. In a combined experimental and theoretical approach, we reveal the intrinsic Rabi oscillation dynamics by monitoring both central exciton quantities, i.e., its occupation and the microscopic coherence, as resolved by the four-wave mixing technique. In the frequency domain, this oscillation generates the Autler–Townes splitting of the light-exciton dressed states, directly seen in the four-wave mixing spectra. We further demonstrate that the coupling to acoustic phonons strongly influences the four-wave mixing dynamics on the picosecond time scale, because it leads to transitions between the dressed states.

中文翻译：

---

耦合声子的量子点激子的拉比振荡：相干性和总体读出

现在，通常在低频（千兆赫兹）系统（如单自旋）中常规执行量子位的高级相干控制，但要在光域中实现两级系统则要困难得多。这是因为后者通常在太赫兹范围内发展，因此需要超快速，相干，非线性光学的工具。使用四波混合显微技术，我们在这里测量局限在半导体量子点中的单个激子量子态的光学驱动动力学。在实验和理论相结合的方法中，我们通过监测中心激子数量（即其占据和微观相干性）（通过四波混合技术解决），揭示了固有的拉比振荡动力学。在频域中 这种振荡产生了光激子修整状态的Autler–Townes分裂，可直接在四波混频光谱中看到。我们进一步证明，与声子的耦合会在皮秒级的时间范围内强烈影响四波混频动力学，因为它会导致在修整状态之间进行转换。