  An attractive implementation for quantum cryptography is the continuous
variable variation, as it relies on standard telecommunication components.
Modulating the quantum signal using a Gaussian format is attractive since it
has been proven to be secure. This work investigates the effect of the roll-off
of a root raised cosine pulse shaping and matched filter on the excess noise
performance of a Gaussian modulated quantum key distribution system in a
simulated back to back configuration. Contrary to intuition, it is found that
the roll-off parameter does not significantly impact the performance of the
system.
