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Figure 2 | EPJ Quantum Technology

Figure 2

From: Gain, noise and intermodulation in a nonlinear superconducting resonator

Figure 2

Microwave noise power is calibrated in a narrow band centered at the frequency f c =7.62 GHz, by varying the temperature of the 50 Ω termination on the cold circulator. A one-parameter fit to Eq. (5), adjusting only the overall gain factor, allows for determination of the HEMT amplifiers noise temperature T N HEMT =2.62 K and observation of the quantum noise T Q =0.18 K. The data points in the inset are the quantum noise at different center frequencies in the band of the HEMT amplifier, and the straight line is the expected behavior T Q = h f c 2 k B .

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