  Moir\'e potentials in two-dimensional materials have been proven to be of
fundamental importance to fully understand the electronic structure of van der
Waals heterostructures, from superconductivity to correlated excitonic states.
However, understanding how the moir\'e phonons, so-called phasons, affect the
properties of the system still remains an uncharted territory. In this work, we
demonstrate how phasons are integral to properly describing and understanding
low-temperature interlayer exciton diffusion in WS2/WSe2 heterostructure. We
perform photoluminescence (PL) spectroscopy to understand how the coupling
between the layers, affected by their relative orientation, impacts the
excitonic properties of the system. Samples fabricated with stacking angles of
0{\deg} and 60{\deg} are investigated taking into account the stacking angle
dependence of the two common moir\'e potential profiles. Additionally, we
present spatially and time-resolved exciton diffusion measurements, looking at
the photoluminescence emission in a temperature range from 30 K to 250 K. An
accurate potential for the two configurations are computed via density
functional theory (DFT) calculations. Finally, we perform molecular dynamics
simulation in order to visualize the phasons motion, estimating the phason
speed at different temperatures, providing novel insights into the mechanics of
exciton propagation at low temperatures that cannot be explained within the
frame of classical exciton diffusion alone.
