利用动力学势垒测量电子波包的到达时间
Measuring the arrival time of an electron wave packet using a dynamical potential barrier
AI总结：
本文研究时变势垒测量热电子波包到达时间时因有限上升速度导致的误差，区分半经典与准静态区域并给出精确检测的时间尺度条件。
摘要：
通过在波包到达势垒时升高势垒以阻挡波包，时变势垒已被用于探测热电子波包的到达时间分布。为考察该势垒能否精确检测该分布，有必要研究由势垒有限上升速度引起的误差。为此，我们研究电子波包通过动力学势垒的透射，并识别出两种区域：半经典区域和准静态区域。在每种区域中，我们计算利用该势垒重建的到达时间分布，并量化检测中的误差，即波包分布与重建分布之间时间不确定度的差异。我们的发现表明，为实现精确检测，势垒高度在波包能量分布及势垒隧穿能量窗口之上上升所用的时间尺度，必须远短于波包的时间不确定度。解析结果得到了数值计算的证实。
英文摘要：
A time-dependent potential barrier has been used to probe the arrival-time distribution of the wave packet of a hot electron by raising the barrier to block the packet upon arrival of the packet at the barrier. To see whether the barrier precisely detects the distribution, it is necessary to study an error caused by a finite rising speed of the barrier. For this purpose, we study transmission of an electron wave packet through the dynamical barrier, and identify two regimes, the semiclassical regime and the quasistatic regime. In each regime, we calculate the arrival-time distribution reconstructed by using the barrier and quantify the error in the detection, the difference of the temporal uncertainty between the wave-packet distribution and the reconstructed distribution. Our finding suggests that for precise detection, the time scale, in which the barrier height rises over the energy distribution of the wave packet and the tunneling energy window of the barrier, has to be much shorter than the temporal uncertainty of the wave packet. The analytical results are confirmed with numerical calculations.
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