Abstract
This thesis contains the theoretical work produced to achieve three goals. Firstly, by
understanding the basics of density matrices and open quantum systems, the intricacies of
the equations of motion could be understood and a new, key feature, the window operator,
could be added to the coupled-channel density-matrix (CCDM) model. From this, the
addition of quantum observable calculations such as entropy, energy dissipation and purity
were made possible, but more importantly this permitted the calculation of energy-resolved
fusion probabilities that were previously unobtainable with this fully quantum dynamical
method.
The next step was motivated by the curiosity of heavy-ion fusion in hot, dense plasmas. A
review of the potential effects of plasma on heavy-ion fusion reactions was conducted, and
significant results were found for one attribute of the plasma: temperature. It is known
that the higher-end of plasma temperatures in stellar environments become hot enough
that heavy-ions with low-lying excited states are significantly populated prior to a nuclear
reaction. However, this has not been applied to nuclear fusion and hence the CCDM model
was employed to fill this void. Temperature was found to increase fusion probabilities
compared to calculations that did not include temperature effects, and a short theoretical
explanation of the increase was provided.
Finally, the CCDM model was applied in the context of nuclear friction. Using an adjusted
phenomenological friction form factor introduced by Gross and Kalinowski, the effects of
friction were included as an environment. The inclusion of friction resulted in increased
fusion probabilities compared to frictionless calculations, and an improvement on the barrier
distribution when comparing theory to experimental results.