We study an integrable Hamiltonian reducible to free fermions which is
subjected to an imperfect periodic driving with the amplitude of driving (or
kicking) randomly chosen from a binary distribution like a coin-toss problem.
The randomness present in the driving protocol destabilises the periodic steady
state, reached in the limit of perfectly periodic driving, leading to a
monotonic rise of the stroboscopic residual energy with the number of periods
(N). We establish that a minimal deviation from the perfectly periodic
driving would always result in a {\it bounded} heating up of the system with
N to an asymptotic finite value. Remarkably, exploiting the completely
uncorrelated nature of the randomness and the knowledge of the stroboscopic
Floquet operator in the perfectly periodic situation, we provide an exact
analytical formalism to derive the disorder averaged expectation value of the
residual energy through a {\it disorder operator}. This formalism not only
leads to an immense numerical simplification, but also enables us to derive an
exact analytical form for the residual energy in the asymptotic limit which is
universal, i.e, independent of the bias of coin-toss and the protocol chosen.
Furthermore, this formalism clearly establishes the nature of the monotonic
growth of the residual energy at intermediate N while clearly revealing the
possible non-universal behaviour of the same.Comment: 14 pages, 5 figure
