Cryogenic amplifiers with superconducting LC resonator for low Temperatur NMR

Frédéric Ayela, J-.L. Bret, J. Chaussy

Akiyoshi Tomonaga, Hiroto Mukai, Jaw-Shen Tsai

C.J. Ballard, Rangga P. Budoyo, Kristen Voigt +3 more

Boris I Ivanov, Dmitry I. Volkhin, Ilya L. Novikov +5 more

A broadband low-noise four-stage high-electron-mobility transistor amplifier was designed and characterized in a cryogen-free dilution refrigerator at the 3.8 K temperature stage. The obtained power dissipation of the amplifier is below 20 mW. In the frequency range from 6 to 12 GHz its gain exceeds 30 dB. The equivalent noise temperature of the amplifier is below 6 K for the presented frequency range. The amplifier is applicable for any type of cryogenic microwave measurements. As an example we demonstrate here the characterization of the superconducting X-mon qubit coupled to an on-chip coplanar waveguide resonator.

Charles Neill, A. Megrant, M. Lenander +17 more

Yuma Okazaki, Nobu‐Hisa Kaneko

We propose a new type of cryogenic current amplifiers, in which low-frequency power spectrum of current can be measured through a measurement of microwave response of a superconducting resonant circuit shunted by a series array of Josephson junctions. From numerical analysis on the equivalent circuit, the numerical value of the input-referred current noise of the proposed amplifier is found to be two orders of magnitude lower than the noise floor measured with the conventional cryogenic current amplifiers based on high-electron-mobility transistors or superconducting quantum interference devices. Our proposal can open new avenues for investigating low-temperature solid-state devices that require lower noise and wider bandwidth power spectrum measurements of current.