  We theoretically study a scheme to develop an atomic based MW interferometry
using the Rydberg states in Rb. Unlike the traditional MW interferometry, this
scheme is not based upon the electrical circuits, hence the sensitivity of the
phase and the amplitude/strength of the MW field is not limited by the Nyquist
thermal noise. Further this system has great advantage due to its very high
bandwidth, ranging from radio frequency (RF), micro wave (MW) to terahertz
regime. In addition, this is \textbf{orders of magnitude} more sensitive to
field strength as compared to the prior demonstrations on the MW electrometry
using the Rydberg atomic states. However previously studied atomic systems are
only sensitive to the field strength but not to the phase and hence this scheme
provides a great opportunity to characterize the MW completely including the
propagation direction and the wavefront. This study opens up a new dimension in
the Radar technology such as in synthetic aperture radar interferometry. The MW
interferometry is based upon a six-level loopy ladder system involving the
Rydberg states in which two sub-systems interfere constructively or
destructively depending upon the phase between the MW electric fields closing
the loop.
