High-sensitivity microwave vector detection at extremely low-power   levels for low-dimensional electron systems
  We present a high-sensitivity microwave vector detection system for studying the low-dimensional electron system embedded in the gaps of a coplanar waveguide at low temperatures. Using this system, we have achieved 0.005% and 0.001\textdegree resolutions in amplitude and phase variations, respectively, at 10 GHz in a magnetotransport measurement on a quantum-wire array with an average signal power less than $-$75 dBm into the sample at 0.3 K. From the measured phase variation, we can distinguish a very tiny change in the induced dipole moment of each quantum wire. 
W. H. Hsieh, C. H. Kuan, Y. W. Suen, S. Y. Chang, L. C. Li B. C. Lee,   and C. P. Lee