Compact microwave kinetic inductance nanowire galvanometer for cryogenic detectors at 4.2 K

TL;DR

This paper introduces a compact, simplified superconducting microwave nanowire galvanometer operating at 4.2 K, capable of multiplexed readout for cryogenic detector arrays with low noise and pulse amplification.

Contribution

It presents a novel, easy-to-fabricate superconducting resonator-based current sensor suitable for cryogenic applications and multiplexed readout, improving on existing approaches.

Findings

Achieved a current noise floor of 10 pA/Hz^{1/2} at 10 kHz.

Demonstrated effective amplification of superconducting nanowire single-photon detector signals.

Enabled frequency-division multiplexing with GHz-range carrier.

Abstract

We present a compact current sensor based on a superconducting microwave lumped-element resonator with a nanowire kinetic inductor, operating at 4.2 K. The sensor is suitable for multiplexed readout in GHz range of large-format arrays of cryogenic detectors. The device consists of a lumped-element resonant circuit, fabricated from a single 4-nm-thick superconducting layer of niobium nitride. Thus, the fabrication and operation is significantly simplified in comparison to state-of-the-art approaches. Because the resonant circuit is inductively coupled to the feed line the current to be measured can directly be injected without having the need of an impedance matching circuit, reducing the system complexity. With the proof-of-concept device we measured a current noise floor {\delta}Imin of 10 pA/Hz1/2 at 10 kHz. Furthermore, we demonstrate the ability of our sensor to amplify a pulsed response of a superconducting nanowire single-photon detector using a GHz-range carrier for effective frequency-division multiplexing.