  We propose an interferometry technique, by using electromagnetically induced
transparency phenomena, for measuring classical force. The classical force is
estimated by measuring the phase at the output of the interferometer. The
proposed measurement mechanism satisfies quantum non-demolition measurement
conditions leading to back-action evasion. We further derive the sufficient
condition under which the thermal noise in the interferometer is negligible.
With no back-action noise and no thermal noise, the sensitivity of this
technique is limited by shot noise only.
