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arXiv 0907.1792quant-ph
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具有协变测量的调谐时间

Tunneling times with covariant measurements

J. Kiukas, A. Ruschhaupt, R. F. Werner

摘要:

我们考虑大质量的,非相对论性的,一维粒子由于隧穿势的时间延迟。在这种情况下,著名的哈特曼效应断言,通常通过隧道的粒子子系综似乎瞬间穿过隧道区域。利用这种效应获得更快信号的一个障碍是隧道的指数衰减,因此在加速和强度之间似乎存在权衡。在本文中,我们证明了这种权衡是从来没有在更快的信号的青睐:一个信号到达其目的地的概率在一些截止日期之前总是减少隧道,为任意传入状态,任意正和compressible支持隧道电位,和任意检测器。更具体地说,我们展示了几种不同的方式来定义“相同的传入状态”和“相同的检测器”,当比较有和没有隧道电位的设置时。到达时间的测量表示在时间协变的方法,但我们也允许检测是一个本地化的测量在稍后的时间。

英文摘要:

We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never in favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define ``the same incoming state'' and ''the same detector'' when comparing the settings with and without tunnel potential. The arrival time measurements are expressed in the time-covariant approach, but we also allow the detection to be a localization measurement at a later time.

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