Light-field control of real and virtual charge carriers
Light-field control of real and virtual charge carriers
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DOI：
10.1038/s41586-022-04565-9
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发表时间：
2022-05-12
期刊：
影响因子：
64.8
通讯作者：
Hommelhoff, Peter
中科院分区：
文献类型：
--
作者：
Boolakee, Tobias;Heide, Christian;Hommelhoff, Peter
光驱动的电子激发是能量和信息传递的基石。在强和超快光场与固体的相互作用中，电子可能被不可逆地激发，或者仅在照明期间被瞬时激发。由于在光脉冲消失后不能观察到瞬态电子布居数，所以它被称为虚的，而保持激发的布居数被称为真实的（1，）（4）。虚电荷载流子最近与高次谐波产生和瞬态吸收有关（5-）（8），但光电流产生可能源于真实的以及虚电荷载流子（9，14）。然而，载体类型的产生和它们对技术相关性的重要性之间的联系是缺失的。在这里，我们表明，真实的和虚拟的电荷载流子可以被激发和解开在金-石墨烯-金异质结构中使用几个周期的激光脉冲的电流的光学产生。根据用于光激发的波形，真实的载流子接收净动量并传播到金电极，而虚载流子在金-石墨烯界面处产生读出的偏振响应。在这些见解的基础上，我们进一步证明了未来光波电子学的逻辑门的概念证明。我们的结果为监测和激发真实的和虚拟的载流子提供了一种直接的手段。对每种载波的单独控制将显著增加集成电路设计空间，并使拍赫兹信号处理更接近现实（15-16）。
Light-driven electronic excitation is a cornerstone for energy and information transfer. In the interaction of intense and ultrafast light fields with solids, electrons may be excited irreversibly, or transiently during illumination only. Asthe transient electron population cannot be observed after the light pulse isgone, it is referred to as virtual, whereas the population that remains excited is called real(1,)(4). Virtual charge carriers have recently been associated with high-harmonicgeneration and transient absorption(5-)(8), but photocurrentgeneration may stem from real as well as virtual charge carriers(9,14). However, a link between the generation ofthe carrier types and their importance for observables oftechnological relevance is missing. Here we show that real and virtual charge carriers can be excited and disentangled in the optical generation of currents in a gold-graphene-gold heterostructure using few-cycle laser pulses. Depending on the waveform used for photoexcitation, real carriers receive net momentum and propagate to the gold electrodes, whereasvirtual carriersgenerate a polarization response read out at the gold-graphene interfaces. On the basis ofthese insights, we further demonstrate a proof of concept of a logic gate for future lightwave electronics. Our results offer a direct meansto monitor and excite real and virtual charge carriers. Individual control over each type of carrier will markedly increase the integrated-circuit design space and bring petahertz signal processing closer to reality(15-16).