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Microwave Kinetic Inductance Detectors (MKIDs) are photon detectors comprised of superconducting LC resonators with unique resonant frequencies corresponding to their geometrical structure. As each pixel has its own geometry, electromagnetic simulations by hand of every pixel in a kilo-pixel array are impractical. Simulating fewer pixels and interpolating in between risks reduced pixel yield in arrays due to overlapping resonant frequencies. We introduce a new software called AEM (Automated Electromagnetic MKID simulations) that automates the constructions and simulations of every simulated MKID pixel in an array according to specified resonant frequencies and a Qc range. We show automated designs to have an increased pixel yield (avoiding loses due to interpolation completely), increased accuracy in resonance frequency and Qc values when compared to interpolated structures. We also demonstrate a simulated trial of AEM for 100 MKIDs between 4 & 8 GHz to produce MKIDs with accuracies of +-0.2 MHz with a runtime of 10 hrs 45 mins., Comment: 10 pages, 5 figures, LTD Proceedings Paper 2023

This paper describes the energy resolution of Microwave Kinetic Inductance Detectors (MKIDs), and models some limiting factors to it. Energy resolution is a measure of the smallest possible difference in energy of the impinging photons, Delta E, that the detector can identify and is of critical importance for many applications. Limits to the energy resolution cause by the Fano effect, amplifier noise, current inhomogeneities, and readout sampling frequency are taken into consideration for this model. This paper describes an approach to combine all of these limitations and predict a wavelength dependency of the upper limit to the resolving power.

The Xilinx ZCU111 Radio Frequency System on Chip (RFSoC) is a promising solution for reading out large arrays of microwave kinetic inductance detectors (MKIDs). The board boasts eight on-chip 12-bit / 4.096 GSPS analogue-to-digital converters (ADCs) and eight 14-bit / 6.554 GSPS digital-to-analogue converters (DACs), as well as field programmable gate array (FPGA) resources of 930,000 logic cells and 4,272 digital signal processing (DSP) slices. While this is sufficient data converter bandwidth for the readout of 8,000 MKIDs, with a 2 MHz channel-spacing, and a 1 MHz sampling rate (per channel), additional FPGA resources are needed to perform the DSP needed to process this large number of MKIDs. A solution to this problem is the new Xilinx RFSoC 2x2 board. This board costs only one fifth of the ZCU111 while still providing the same logic resources as the ZCU111, albeit with only a quarter of the data converter resources. Thus, using multiple RFSoC 2x2 boards would provide a better balance between FPGA resources and data converters, allowing the full utilization of the RF bandwidth provided by the data converters, while also lowering the cost per pixel value of the readout system, from approximately EUR2.50 per pixel with the ZCU111, to EUR1 per pixel., Comment: 7 pages, 6 figures. Presented at 19$^{th}$ International Workshop on Low Temperature Detectors, 21$^{st}$ July 2023. Resubmission to correct minor typo in author list

Microwave Kinetic Inductance Detectors (MKIDs) are cryogenic photon detectors and are attractive because they permit simultaneous time, energy and spatial resolution of faint astronomical sources. We present a cost-effective alternative to dedicated (e.g. analogue) electronics for prototyping readout of single-pixel Optical/NIR MKIDs by repurposing existing and well-known ROACH-1 boards. We also present a pipeline that modernises previously-developed software and data frameworks to allow for extensiblity to new applications and portability to new hardware (e.g. Xilinx ZCU111 or 2x2 RFSoC boards)., Comment: 7 pages, 4 figures, Presented at SPIE Astronomical Telescopes + Instrumentation, 2022, Montr\'eal, Qu\'ebec, Canada

Building upon existing signal processing techniques and open-source software, this paper presents a baseline design for an RF System-on-Chip Frequency Division Multiplexed readout for a spatio-spectral focal plane instrument based on low temperature detectors. A trade-off analysis of different FPGA carrier boards is presented in an attempt to find an optimum next-generation solution for reading out larger arrays of Microwave Kinetic Inductance Detectors (MKIDs). The ZCU111 RF SoC FPGA board from Xilinx was selected, and it is shown how this integrated system promises to increase the number of pixels that can be read out (per board) which enables a reduction in the readout cost per pixel, the mass and volume, and power consumption, all of which are important in making MKID instruments more feasible for both ground-based and space-based astrophysics. The on-chip logic capacity is shown to form a primary constraint on the number of MKIDs which can be read, channelised, and processed with this new system. As such, novel signal processing techniques are analysed, including Digitally Down Converted (DDC)-corrected sub-maximally decimated sampling, in an effort to reduce logic requirements without compromising signal to noise ratio. It is also shown how combining the ZCU111 board with a secondary FPGA board will allow all 8 ADCs and 8 DACs to be utilised, providing enough bandwidth to read up to 8,000 MKIDs per board-set, an eight-fold improvement over the state-of-the-art, and important in pursuing 100,000 pixel arrays. Finally, the feasibility of extending the operational frequency range of MKIDs to the 5 - 10 GHz regime (or possibly beyond) is investigated, and some benefits and consequences of doing so are presented.

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., Comment: 8 pages, 7 figures, SPIE Proceedings

In a recent criticism (arXiv:2111.13357) of our paper arXiv:2111.09347, Drezet argues that we have forgotten to consider superpositions of detector eigenstates. However, such superpositions do not occur in the models our paper is concerned with. We also note that no one has ever observed such detector superpositions., Comment: 1 pages, no figures

The Delayed-Choice Quantum Eraser experiment is commonly interpreted as implying that in quantum mechanics a choice made at one time can influence an earlier event. We here suggest an extension of the experiment that results in a paradox when interpreted using a local realist interpretation combined with backward causation ("retrocausality"). We argue that resolving the paradox requires giving up the idea that, in quantum mechanics, a choice can influence the past, and that it instead requires a violation of Statistical Independence without retrocausality. We speculate what the outcome of the experiment would be., Comment: 8 pages, 6 figures. v2: minor fixes, references added