Discord and decoherence

In quantum information theory, discord has been proposed as a tool to characterise the presence of "quantum correlations" between subparts given system. Whether system behaves quantum-mechanically or classically is believed be impacted by phenomenon decoherence, which originates from unavoidable interaction this and an environment. Generically, decoherence associated with decrease state purity, i.e. transition pure mixed state. paper, we investigate how modified quantum-to-classical transition. This study carried out on systems described quadratic Hamiltonians Gaussian states, generalised squeezing parameters. A generic parametrisation also introduced describe way partitioned into two subsystems. We find that evolution in environment competition growth amplitude purity. phase space, corresponds whether semi-minor axis Wigner ellipse increases decreases, clear geometrical interpretation. Finally, these considerations are applied primordial cosmological perturbations, thus allowing us large-scale structures our universe, arise fluctuations, can exhibit classical properties.