  We show an electron interferometer between a quantum point contact (QPC) and
a scanning gate microscope (SGM) tip in a two-dimensional electron gas. The QPC
and SGM tip act as reflective barriers of a lossy cavity; the conductance
through the system thus varies as a function of the distance between the QPC
and SGM tip. We characterize how temperature, electron wavelength, cavity
length, and reflectivity of the QPC barrier affect the interferometer. We
report checkerboard interference patterns near the QPC and, when injecting
electrons above or below the Fermi energy, effects of dephasing.
