  The Kitaev model exhibits a canonical quantum spin liquid as a ground state
and hosts two fractional quasiparticles, itinerant Majorana fermion and
localized flux excitation. The former can carry heat and spin modulations in
the quantum spin liquid, but the role of the latter remains unknown for the
transport phenomena. Here, we focus on spin transport in the presence of
excited fluxes and report that they yield strong interference in the
propagation of the Majorana fermions, which feel gauge-like potential emergent
around the fluxes. We examine the transient spin dynamics triggered by a pulsed
magnetic field at an edge. In the absence of excited fluxes, the magnetic-field
pulse creates the plane wave of the Majorana fermions, which flows in the
quantum spin liquid. Although this wave does not accompany the change of local
spin moments in bulk, it induces local moments at the side opposite to the edge
under the magnetic-field pulse. We observe the spatial modulation of induced
spin moments when fluxes are excited in the bulk region. This behavior is more
striking than the case of lattice defects. Moreover, we find that, although the
amplitude of the spatial change is almost independent of the distance between
lattice defects, it is strongly enhanced by increasing the distance for the
case of excited fluxes. The difference is understood from the influence on the
itinerant Majorana fermions; the lattice defects change the system locally, but
flux excitations alter all the transfer integrals on the string connecting
them. The present results will provide another route to observing intrinsic
flux excitations distinguished from extrinsic effects such as lattice defects.
