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(Color online) Device diagram and measurement schematic. (a) Device’s center conductor is a series array of 400 SQUIDs. The resonator’s ground plane is made out of aluminum and the SQUIDs are made from junctions. They are fabricated using e-beam lithography and double angle evaporation on an oxidized silicon substrate. (b) Simplified measurement schematic. We model the resonator as a RLC circuit, as shown in the dashed box.
(Color online) Flux and power dependences of the resonance circuit. (a) Resonance frequency as a function of flux. (b) Reflection coefficient magnitude as a function of frequency at different pump powers for .
(Color online) Performance of the amplifier in nondegenerate mode. [(a) and (b)] DG and IG as functions of signal detuning (points) and predictions of Ref. 12 (lines) for two different pump powers. DG and IG for (black) and for (red). [(c) and (d)] DG and IG as functions of pump detuning (points) for (blue) and (red) and prediction (lines) of Ref. 12.
(Color online) Performance of the amplifier in degenerate mode. (a) Gain as a function of the phase between the pump and the signal (points) and prediction (line) from Ref. 12. (b) Power spectral density of the demodulator output for the cases when the pump is on and off. The gain in this case is . The applied signal power is .
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