Equivalence of Optical and Electrical Noise Equivalent Power of Hybrid NbTiN-Al Microwave Kinetic Inductance Detectors

TL;DR

This study demonstrates that the optical and electrical noise equivalent power of hybrid NbTiN-Al MKIDs are comparable, enabling NEP estimation from dark measurements, which simplifies detector characterization.

Contribution

The paper shows the equivalence of optical and electrical NEP in hybrid NbTiN-Al MKIDs, providing a method to estimate NEP without optical illumination.

Findings

Electrical NEP is within a factor of two of optical NEP.

Optical and electrical stimuli produce equivalent effects on MKID resonance.

Dark environment measurements can reliably estimate NEP.

Abstract

We have measured and compared the response of hybrid NbTiN-Al Microwave Kinetic Inductance Detectors (MKIDs) to changes in bath temperature and illumination by sub-mm radiation. We show that these two stimulants have an equivalent effect on the resonance feature of hybrid MKIDs. We determine an electrical NEP from the measured temperature responsivity, quasiparticle recombination time, superconducting transition temperature and noise spectrum, all of which can be measured in a dark environment. For the two hybrid NbTiN-Al MKIDs studied in detail the electrical NEP is within a factor of two of the optical NEP, which is measured directly using a blackbody source.