Bypassing the energy-time uncertainty in time-resolved photoemission
Bypassing the energy-time uncertainty in time-resolved photoemission
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DOI：
10.1103/physrevb.95.115132
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发表时间：
2016-04
影响因子：
3.7
通讯作者：
F. Randi;D. Fausti;M. Eckstein
中科院分区：
文献类型：
--
作者：
F. Randi;D. Fausti;M. Eckstein
能量-时间不确定度是时间分辨实验的内在限制，它在实验中使用的光脉冲的持续时间和它们的频率含量之间进行权衡。在标准的时间分辨光电发射中，这种限制直接映射到实验的时间分辨率和电子光谱函数所能达到的能量分辨率之间的权衡。在这里，我们提出了一个协议，以解开光电发射中的能量分辨率和时间分辨率。我们证明，所有时间尺度上的动态信息都可以通过使用量子或经典性质的适当形状的光脉冲的时间分辨光电子发射实验来检索。作为一个典型的例子，我们研究了近藤峰的动态建立，这是由于传导电子屏蔽磁性杂质而产生的电子响应函数中的一个窄特征。在猝灭后，电子屏蔽建立在比近藤峰的反宽度更短的时间尺度上，我们证明所提出的实验方案可以用来测量这种电子屏蔽的固有时间尺度。提出的方法提供了一个实验框架，可以获得超出光谱不确定极限的集体电子性质的非平衡响应，并将能够直接测量诸如激发的Higgs模以及可能的超导系统中的延迟相互作用等现象。
The energy-time uncertainty is an intrinsic limit for time-resolved experiments imposing a tradeoff between the duration of the light pulses used in experiments and their frequency content. In standard time-resolved photoemission, this limitation maps directly onto a tradeoff between the time resolution of the experiment and the energy resolution that can be achieved on the electronic spectral function. Here we propose a protocol to disentangle the energy and time resolutions in photoemission. We demonstrate that dynamical information on all time scales can be retrieved from time-resolved photoemission experiments using suitably shaped light pulses of quantum or classical nature. As a paradigmatic example, we study the dynamical buildup of the Kondo peak, a narrow feature in the electronic response function arising from the screening of a magnetic impurity by the conduction electrons. After a quench, the electronic screening builds up on timescales shorter than the inverse width of the Kondo peak and we demonstrate that the proposed experimental scheme could be used to measure the intrinsic time scales of such electronic screening. The proposed approach provides an experimental framework to access the nonequilibrium response of collective electronic properties beyond the spectral uncertainty limit and will enable the direct measurement of phenomena such as excited Higgs modes and, possibly, the retarded interactions in superconducting systems.