Multiplexable frequency retuning of MKID arrays using their non-linear kinetic inductance

TL;DR

This paper introduces a novel method to individually re-tune MKID resonators by leveraging their non-linear kinetic inductance, thereby reducing frequency collisions and increasing array yield for astronomical imaging.

Contribution

It presents an innovative pixel design that enables multiplexable frequency retuning of MKID arrays using DC bias, addressing previous limitations related to losses and multiplexing.

Findings

Successful re-tuning of colliding resonators demonstrated

Increased pixel yield in MKID arrays achieved

Reduced electromagnetic losses with new pixel design

Abstract

Microwave Kinetic Inductance Detector (MKID) arrays are currently being developed and deployed for astronomical applications in the visible and near infrared and for sub-millimetre astronomy. One of the main drawbacks of MKIDs is that large arrays would exhibit a pixel yield, the percentage of individually distinguishable pixels to the total number of pixels, of 75 - 80 %. Imperfections arising during the fabrication can induce an uncontrolled shift in the resonance frequency of individual resonators which can end up resonating at the same frequency of a different resonator. This makes a number of resonators indistinguishable and therefore unusable for imaging. This paper proposes an approach to individually re-tune the colliding resonators in order to remove the degeneracy and increase the number of MKIDs with unique resonant frequencies. The frequency re-tuning is achieved through a DC bias of the resonator, the kinetic inductance of a superconducting thin film is current dependent and its dependence is non linear. Even though this approach has been already proposed, an innovative pixel design, described in this paper, may solve two issues previously described in literature such as increased electromagnetic losses to the DC-bias line, and the multiplexibility of multiple resonators on a single feedline.