1305.4197 (Xin Chen)

Quantum Path Interference through Incoherent Motions in Multilevel
Quantum Systems    [PDF]

Xin Chen

The fluctuating incoherent environment in the condensed phase plays an important role in the dynamics and steady states of open quantum systems. The most fascinating aspect in open quantum systems is quantum coherence induced by path interference of incoherent motions. We propose a modified Ehrenfest scheme to study the path interference of incoherent motions in multi-level quantum systems. The detailed balance is enforced by considering the quantum correction of two-time correction functions based on second order master (rate) equations. With the modified Ehrenfest method, we can study the steady state populations and other quantum observables under different thermal dynamic conditions, such as energy relaxation and non-Markovian effects. For the three level system under incoherent coupling, we show how the steady state populations are influenced by the quantum path interference of incoherent fluctuations (Agarwal-Fano-like interference). We discuss the modified Ehrenfest method and its connection with stochastic Langevin equations and second order master equations. Most existing quantum MD simulation methods, particularly Master equation techniques, fall into the category of the weak coupling limit due to the nature of detailed balance. Although the modified Ehrenfest method is amicable to second-order master equations, it is actually a better way to model the quantum path interference since it preserves multi-time memory kernels. Therefore, it enables us to study the quantum path interference. This method can be used as quantum MD simulators for large open quantum systems like solar cell, (organic) LED, etc. The future extension of this method beyond the modified Ehrenfest scheme can be done with efficient wavepacket propagation methods by treating the bath modes in full quantum mechanical way.

View original: http://arxiv.org/abs/1305.4197