Heide Christian, Eckstein Timo, Boolakee Tobias, Gerner Constanze, Weber Heiko B, Franco Ignacio, Hommelhoff Peter
Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstrasse 1, D-91058 Erlangen, Germany.
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Nano Lett. 2021 Nov 24;21(22):9403-9409. doi: 10.1021/acs.nanolett.1c02538. Epub 2021 Nov 4.
Electronic coherence is of utmost importance for the access and control of quantum-mechanical solid-state properties. Using a purely electronic observable, the photocurrent, we measure a lower bound of the electronic coherence time of 22 ± 4 fs in graphene. The photocurrent is ideally suited to measure electronic coherence, as it is a direct result of coherent quantum-path interference, controlled by the delay between two ultrashort two-color laser pulses. The maximum delay for which interference between the population amplitude injected by the first pulse interferes with that generated by the second pulse determines the electronic coherence time. In particular, numerical simulations reveal that the experimental data yields a lower bound on the electronic coherence time, masked by coherent dephasing due to the broadband absorption in graphene. We expect that our results will significantly advance the understanding of coherent quantum control in solid-state systems ranging from excitation with weak fields to strongly driven systems.
电子相干对于量子力学固态特性的获取和控制至关重要。我们利用纯电子可观测量光电流，测量出石墨烯中电子相干时间的下限为22±4飞秒。光电流非常适合用于测量电子相干，因为它是相干量子路径干涉的直接结果，由两个超短双色激光脉冲之间的延迟控制。第一个脉冲注入的布居振幅与第二个脉冲产生的布居振幅之间发生干涉的最大延迟决定了电子相干时间。特别是，数值模拟表明，实验数据得出了电子相干时间的下限，该下限被石墨烯中宽带吸收导致的相干退相所掩盖。我们预计，我们的结果将显著推进对固态系统中相干量子控制的理解，这些系统涵盖从弱场激发到强驱动系统。
