  We present results on a multiple-optical-path quantum interference project
suitable for the advanced undergraduate laboratory. The experiments combine a
conceptually rich set of atomic physics experiments which may be economically
developed at a technical level accessible to undergraduate physics or
engineering majors. In the experiments, diode-laser driven two-quantum,
two-color excitation of cesium atoms in a vapor cell is investigated and
relative strengths of the individual hyperfine components in the $6s^{2}S_{1/2}
\rightarrow 7s^{2}S_{1/2}$ transition are determined. Measurement and analysis
of the spectral variation of the two quantum excitation rate clearly shows
strong variations due to interfering amplitudes in the overall transition
amplitude. Projects such as the one reported here allow small teams of
undergraduate students with combined interests in experimental and theoretical
physics to construct instrumentation, perform sophisticated experiments, and do
realistic modelling of the results.
