Chemical and Biological Physics Department , Weizmann Institute of Science , 76100 Rehovot , Israel.
J Phys Chem A. 2018 Apr 12;122(14):3563-3571. doi: 10.1021/acs.jpca.8b01772. Epub 2018 Apr 2.
The time it takes a particle to tunnel through the asymmetric Eckart barrier potential is investigated using Gaussian wavepackets, where the barrier serves as a model for the potential along a chemical reaction coordinate. We have previously shown that the, in principle experimentally measurable, tunneling flight time, which determines the time taken by the transmitted particle to traverse the barrier, vanishes for symmetric potentials like the Eckart and square barrier [ Petersen , J. ; Pollak , E. J. Phys. Chem. Lett. 2017 , 9 , 4017 ]. Here we show that the same result is obtained for the asymmetric Eckart barrier potential, and therefore, the zero tunneling flight time seems to be a general result for one-dimensional time-independent potentials. The wavepacket dynamics is simulated using both an exact quantum mechanical method and a classical Wigner prescription. The excellent agreement between the two methods shows that quantum coherences are not important in pure one-dimensional tunneling and reinforces the conclusion that the tunneling flight time vanishes.
利用高斯波包研究了粒子穿过非对称 Eckart 势垒的时间，该势垒可用作化学反应坐标上的势模型。我们之前已经表明，对于像 Eckart 和方势垒这样的对称势，原则上可以通过实验测量的隧穿飞行时间（即传输粒子穿过势垒所需的时间）会消失[Petersen，J.；Pollak，E. J. Phys. Chem. Lett. 2017，9，4017]。在这里，我们表明对于非对称 Eckart 势垒也得到了相同的结果，因此，对于一维时不变势，零隧穿飞行时间似乎是一个普遍结果。波包动力学是使用精确的量子力学方法和经典的 Wigner 配方进行模拟的。两种方法之间的极好一致性表明，在纯一维隧穿中量子相干并不重要，并加强了隧穿飞行时间消失的结论。
