Fig. 4: Noise characterization.
From: Kerr reversal in Josephson meta-material and traveling wave parametric amplification
a Noise temperature of the amplification chain (green) and the reversed Kerr TWPA (blue) compared to the standard quantum limit (SQL) across amplification band in terms of number of added photons. The device is pumped at 8 GHz and tuned to external magnetic flux Φext/Φ0 = 0.5. The blue shadow area indicates the result of the theoretical simulations considering power dependent losses. b Corresponding gain profile. c Comparison between output noise power fitted to noise models including and excluding idler mode noise input. Ignoring idler mode inaccurately leads to lower noise temperature estimates. d Comparison of simulated noise output for the noise models including and excluding idler mode with identical TWPA noise temperature.
