Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2π area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.

半导体量子点是皮秒级或什至更快的激光脉冲超快速相干操纵量子比特的极佳候选者。在不均匀的集合中，由于相移，宏观的光学偏振会迅速衰减，但是，在携带有关相干集合动力学完整信息的光子回波中，这是可逆的。对于应用，必须控制回声发射时间。在这里，我们提出了一个实现这一目标的概念。在双脉冲光子回波序列，我们应用一个附加谐振控制脉冲以2的倍数π区。根据其到达时间，控件会在其动作期间减慢激子集合的移相或移相速度。对于自组装的（In，Ga）As量子点，我们证明，相对于无控制的标称出现时间，光子回波发射时间可以延迟或提前5 ps。该通用协议可用于为适当定制的控制脉冲获得明显更长的时间偏移。