Cryogenic Low Noise Amplifiers and Filters for Superconducting Qubit Readout

Abstract

We show an experimental study of superconducting X-mon qubit based on low noise wideband measurement setup. The setup includes wide stop-band low frequency filters with a stopband frequency up to 13 GHz, the broadband low-noise cryogenic microwave amplifier (cLNA) operating at 3.8 K. The obtained power dissipation of the cLNA is below 20 mW, the frequency operating ranges from 6 GHz to 12 GHz with a gain of 30 dB. The equivalent noise temperature of the amplifier is bellow 6 K for the presented frequency range. We demonstrate here the characterization of the superconducting X-mon qubit coupled to an on-chip coplanar waveguide resonator. We show standard qubit experiments: one and two-tones qubit spectroscopy, ac-Stark shift experiments for probing and excitation power sweeps.