  The out-of-time-ordered correlator (OTOC) is a measure of quantum chaos that
is being vigorously investigated. Analytically accessible simple models that
have long been studied in other contexts could provide insights into such
measures. This paper investigates the OTOC in the quantum bakers map which is
the quantum version of a simple and exactly solvable model of deterministic
chaos that caricatures the action of kneading dough. Exact solutions based on
the semiquantum approximation are derived that tracks very well the correlators
till the Ehrenfest time. The growth occurs at the exponential rate of the
classical Lyapunov exponent, but modulated by slowly changing coefficients.
Beyond this time saturation occurs as a value close to that of random matrices.
Using projectors for observables naturally leads to truncations of the unitary
time-$t$ propagator and the growth of their singular values is shown to be
intimately related to the growth of the out-of-time-ordered correlators.
