Figure 2
From: Engineering cryogenic setups for 100-qubit scale superconducting circuit systems
Thermal noise photon numbers. (a) Calculated thermal photon number at MXC as a function of the degree of attenuation at the 4 K stage (blue), CP (green), MXC (red) for a fixed attenuation of 20 dB at the respective other stages (45 K stage and 1 K stage have no attenuators in this example). The calculations are based on Eq. (3). (b) Thermal noise current spectral density at MXC as a function of attenuation at the 4 K stage, calculated using Eq. (4)