  We explore the effects of Markovian bath coupling and initial
position-momentum correlations on the coherence and purity of Gaussian quantum
states. Our analysis focuses on the roles these factors play in the dynamics of
quantum coherence, coherence lengths, and state purity. Our results reveal that
initial position-momentum correlations have a remarkable impact on the quantum
properties of the mixed state. These correlations lead to opposing behaviors in
coherence and purity: as quantum coherence increases in response to stronger
correlations, purity diminishes, and vice versa. This inverse relationship
illustrates the phenomenon where, governed by these initial correlations, a
state with greater mixing can display enhanced quantum coherence compared to a
less mixed state. We also observe an unanticipated coherence freezing
phenomenon, quantified by the relative entropy of coherence. Notably, this
freezing is driven by initial position-momentum correlations, although the
final frozen value is independent of these correlations.
