In this thesis we will theoretically investigate three potentially
useful physical systems, after
first developing the theoretical framework necessary for studying them.
First, we will study
the multiphoton absorption properties of maximally path entangled
number (N00N) states.
This is directly relevant to quantum lithography, and beating the
Rayleigh diffraction limit.
Next, we will develop a new scheme for quantum interferometry: dubbed
coherent-light
boosted super-sensitive quantum interferometry. Which has the potential
to reach below
the shot noise limit for high photon fluxes, and requires no esoteric
detection protocol,
or technological elements which have yet to be developed. Finally we
propose a method
to perform parity detection on the output modes of a Mach-Zehnder
interferometer that
has been fed with two-mode squeezed vacuum. This detection scheme
relies on a double
homodyning technique, that makes intensity correlation measurements at
a series of chosen
bias phases. Sub-Heisenberg sensitivity scaling is expected for this
setup.