# Quantum Diffusion in the Strong Tunneling Regime

## TL;DR

This paper investigates how quantum wavepackets diffuse in noisy environments, revealing how noise and external fields influence diffusion constants, with implications for quantum systems like photosynthesis and solid-state electronics.

## Contribution

It provides a theoretical analysis of quantum diffusion under noise using Landau-Zener solutions, highlighting the effects of external fields and disorder on diffusion behavior.

## Key findings

- Diffusion constant depends on noise characteristics.
- External fields suppress diffusion without inducing drift.
- Results applicable to quantum biological and solid-state systems.

## Abstract

We study the spread of a quantum-mechanical wavepacket in a noisy environment, modeled using a tight-binding Hamiltonian. Despite the coherent dynamics, the fluctuating environment may give rise to diffusive behavior. When correlations between different level-crossing events can be neglected, we use the solution of the Landau-Zener problem to find how the diffusion constant depends on the noise. We also show that when an electric field or external disordered potential is applied to the system, the diffusion constant is suppressed with no drift term arising. The results are relevant to various quantum systems, including exciton diffusion in photosynthesis and electronic transport in solid-state physics.