  A point source interferometer (PSI) is a device where atoms are split and
recombined by applying a temporal sequence of Raman pulses during the expansion
of a cloud of cold atoms behaving approximately as a point source. The PSI can
work as a sensitive multi-axes gyroscope that can automatically filter out the
signal from accelerations. The phase shift arising from rotations is
proportional to the momentum transferred to each atom from the Raman pulses.
Therefore, by increasing the momentum transfer, it should be possibly to
enhance the sensitivity of the PSI. Here, we investigate the degree of
enhancement in sensitivity that could be achieved by augmenting the PSI with
large momentum transfer (LMT) employing a sequence of many Raman pulses with
alternating directions. Contrary to typical approaches used for describing a
PSI, we employ a model under which the motion of the center of mass of each
atom is described quantum mechanically. We show how increasing Doppler shifts
lead to imperfections, thereby limiting the visibility of the signal fringes,
and identify ways to suppress this effect by increasing the effective,
two-photon Rabi frequencies of the Raman pulses. Taking into account the effect
of spontaneous emission, we show that, for a given value of the one-photon Rabi
frequency, there is an optimum value for the number of pulses employed, beyond
which the net enhancement in sensitivity begins to decrease. For a one-photon
Rabi frequency of 200 MHz, for example, the peak value of the factor of
enhancement in sensitivity is ~39, for a momentum transfer that is ~69 times as
large as that for a conventional PSI. We also find that this peak value scales
as the one-photon Rabi frequency to the power of 4/5.
