Weigel Alexander, Sebesta Aleksandar, Kukura Philipp
Physical and Theoretical Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QZ, United Kingdom.
J Phys Chem Lett. 2015 Oct 15;6(20):4032-7. doi: 10.1021/acs.jpclett.5b01748. Epub 2015 Sep 28.
Coherent control uses tailored femtosecond pulse shapes to influence quantum pathways and drive a light-induced process toward a specific outcome. There has been a long-standing debate whether the absorption properties or the probability for population to remain in an excited state of a molecule can be influenced by the pulse shape, even if only a single photon is absorbed. Most such experiments are performed on many molecules simultaneously, so that ensemble averaging reduces the access to quantum effects. Here, we demonstrate systematic coherent control experiments on the fluorescence intensity of a single molecule in the weak-field limit. We demonstrate that a delay scan of interfering pulses reproduces the excitation spectrum of the molecule upon Fourier transformation, but that the spectral phase of a pulse sequence does not affect the transition probability. We generalize this result to arbitrary pulse shapes by performing the first closed-loop coherent control experiments on a single molecule.
相干控制利用定制的飞秒脉冲形状来影响量子路径，并推动光诱导过程朝着特定结果发展。长期以来，一直存在这样的争论：即使只吸收一个光子，分子的吸收特性或处于激发态的粒子数概率是否会受到脉冲形状的影响。大多数此类实验是同时在许多分子上进行的，因此系综平均降低了对量子效应的研究。在这里，我们展示了在弱场极限下对单个分子荧光强度进行的系统相干控制实验。我们证明，干涉脉冲的延迟扫描在傅里叶变换后能重现分子的激发光谱，但脉冲序列的光谱相位不影响跃迁概率。通过对单个分子进行首次闭环相干控制实验，我们将这一结果推广到任意脉冲形状。
