FIG. 4: (Color online) The noise equivalent power (NEP) of the microstrip resonator. The solid line shows the NEP derived from phase shifts only, the dotted line is derived from amplitude data, and the dashed line is the optimal NEP using both amplitude and phase data [14]. The red line is the predicted NEP from Equations 4, 6, and 7 assuming there is 2 dB of loss between the device and a HEMT amplifier with T$_{n}$ = 5 . 5 K. Cleland for useful insights. 1 10 100 1000 10000 Frequency (Hz) 10 − 17 10 − 16 10 − 15 10 − 14 NEP (W Hz − 1/2 ) [1] P.K. Day, H. Leduc, B.A. Mazin, A. Vayonakis, and J. Zmuidzinas, Nature 425 , 817–821 (2003). [2] P. Maloney, N. Czakon, P. Day, J. Gao, J. Glenn, L. H. Golwala, S., B. Mazin, D. Moore, O. Noroozian, H. Nguyen, J. Sayers, J. Schlaerth, J. Vaillancourt, A. Vayonakis, and J. Zmuidzinas, AIP Conference Proceedings , 1185, 176 (2009). [3] D. Moore, B. Mazin, S. Golwala, B. Bumble, J. Gao, B. Young, S. McHugh, P. Day, H. LeDuc, and J. Zmuidzinas, AIP Conference Proceedings , 1185, 168 (2009). [4] B. A. Mazin, B. Bumble, P. K. Day, M. E. Eckart, S. Golwala, J. Zmuidzinas, and F. A. Harrison, Appl. Phys. Lett. 89 , 222507 (2006). [5] A. Wallraff, D. Schuster, A. Blais, L. Frunzio, R. Huang, J. Majer, S. Kumar, S. Girvin, and R. Schoelkopf, Nature 431 , 162–167 (2004). [6] J. Martinis, K. Cooper, R. McDermott, M. Steffen, M. Ansmann, K. Osborn, K. Cicak, S. Oh, D. Pappas, R. Simmonds, and C. Yu, Phys Rev Lett 95 , 210503 (2005). 9