Quantum coherence in the reflection of above barrier wavepackets

Area of Science:

• Quantum Mechanics
• Physical Chemistry
• Surface Science

Background:

• Above barrier reflection is a fundamental quantum phenomenon.
• Understanding the temporal dynamics of quantum scattering is crucial for various fields.

Purpose of the Study:

• Investigate above barrier reflection using a time-dependent approach.
• Analyze mean flight times for reflection and transmission over a barrier.
• Examine the dependence of these times on barrier width and wavepacket characteristics.

Main Methods:

• Utilized Gaussian wavepackets for time-dependent quantum mechanical simulations.
• Analyzed transition path time distributions to determine mean flight times.
• Studied the impact of barrier width and wavepacket-to-barrier width ratio on dynamics.

Main Results:

• Identified two distinct regimes: coherent (wavepacket width > barrier length) and incoherent (wavepacket width < barrier length).
• Coherent regime shows oscillatory flight times and differences, linked to resonances and momentum filtering.
• Incoherent regime lacks oscillations; wavepackets split temporally, with classical Wigner approximation proving quantitative.

Conclusions:

• Wigner phase time does not accurately capture temporal properties of above barrier reflection.
• Wavepacket structure differs significantly between coherent and incoherent regimes.
• Coherence plays a critical role in resonance reactive scattering.