  We study the effects of arbitrary laser pulse excitations on quantum
correlation, entanglement and the role of quantum noise. The transient
quantities are computed exactly using a method that provides exact solutions of
the Langevin field operators for photon pairs produced by a double Raman atom
driven by laser pulses. Short pulses with appropriate chirping, delay and/or
detuning can generate broadband photon pairs and yield results that provide
insights on how to generate very large nonclassical correlation. We find that
short pulses are not favorable for entanglement. The quantity was previously
found to be phase-sensitive and this is used with the pulse area concept to
explain the rapid variations of entanglement with pulse width and strength.
Photon correlation and entanglement are favored by exclusively two different
initial conditions. Analysis reinforces our understanding of the two
nonclassical concepts.
