  The quantum dynamics of isolated systems under quench condition exhibits a
variety of interesting features depending on the integrable/chaotic nature of
system. We study the exact dynamics of trivially integrable system of harmonic
chains under a multiple quench protocol. Out of time ordered correlator of two
Hermitian operators at large time displays scrambling in the thermodynamic
limit. In this limit, the entanglement entropy and the central component of
momentum distribution both saturate to a steady state value. We also show that
reduced density matrix assumes the diagonal form long after multiple quenches
for large system size. These exact results involving infinite dimensional
Hilbert space are indicative of local thermal behaviour for a trivially
integrable harmonic chain.
