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Séminaire spécial

Vendredi le 21 fevrier à 15h30,
Salle Louis Weil, E424

Orateur : Xin Zhou (SPEC, DSM/IRAMIS, CNRS URA 2464)
"High-gain weakly nonlinear flux-modulated Josephson parametric amplifier using a SQUID-array"

Abstract

Although superconducting parametric amplifiers based on Josephson junctions have been around for decades, they were given a recent boost because of their ability to measure quantum objects like superconducting qubits or mechanical resonators at or near the quantum limit, as well as for their ability to squeeze quantum noise for fundamental physics experiments. Nevertheless, compared to the noisier high electron mobility transistor (HEMT) based amplifiers, these Josephson parametric amplifiers (JPA) suffer from limited bandwidth and from gain saturation at extremely low input power. In this work, we show our efforts on testing the idea of parametric pumping based on 3-wave mixing (such that ωP = ωS + ωI ) and demonstrate a weakly non-linear JPA with high gain, made of a lumped LC resonator with the inductor L terminated by a SQUID array. The presentation will first summarize the theoretical description of such a JPA and give a general design rule of this kind amplifier. Then we describe the device fabrication and its characterization setup, and finally present the experimental data and a comparison between measured and calculated gain, bandwidth, and saturation.

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