  We study quantum non-Markovian dynamics of the Caldeira-Leggett model, a
prototypical model for quantum Brownian motion describing a harmonic oscillator
linearly coupled to a reservoir of harmonic oscillators. Employing the exact
analytical solution of this model one can determine the size of memory effects
for arbitrary couplings, temperatures and frequency cutoffs. Here, quantum
non-Markovianity is defined in terms of the flow of information between the
open system and its environment, which is quantified through the Bures metric
as distance measure for quantum states. This approach allows us to discuss
quantum memory effects in the whole range from weak to strong dissipation for
arbitrary Gaussian initial states. A comparison of our results with the
corresponding results for the spin-boson problem show a remarkable similarity
in the structure of non-Markovian behavior of the two paradigmatic models.
