Fig. 2
Noise equivalent power (NEP) and thermal time constant. a–d Quasistatic responsivity of the probe voltage to the heater power (a, b) and probe voltage spectral density (c, d) as functions of probe frequency and power with the Josephson parametric amplifier (JPA) off (a, c) and on (b, d) averaged over noise frequencies between 20 and 100 Hz. e, f Noise equivalent power as a function of probe frequency and power with the JPA off (e) and on (f) averaged over noise frequencies between 20 and 100 Hz. g, h NEP (black) and thermal time constant (red) with the JPA off at fixed Pp = −126 dBm (g) and with the JPA on at Pp = −126.5 dBm (h). The error bars indicate the standard error of the mean for the time constant and error arising from heater power calibration for NEP
