arXiv subjects

Karia Dibert

Publications and source records attributed to Karia Dibert.

6 recordsLinked to original sources

arXiv2026

A waveguide spectrometer for high-resolution millimeter-wave imaging

We present the design and development of a novel, compact integrated on-chip spectrometer operating at millimeter (mm) and submillimeter (sub-mm) wavelengths. The Superconducting Waveguide Integrated Submillimeter Spectrometer (SWISS) promises significant improvements in spectral resolution, optical efficiency, and frequency coverage over current mm-wave spectrometers by using a free-space rectangular waveguide architecture. Light is coupled in through the antenna front end, which separates the two polarizations and passes them to the waveguide spectrometer through a contactless metamaterial transition. Each waveguide spectrometer consists of a feedline coupled to a series of filters based on single-pole cavity resonators with varying resonant frequencies. To maximize packing density, the filter banks are oriented out of the focal plane, and an E-plane bend in the output from the cavity filters enables a planar and scalable construction. The output of each filter is coupled to a kinetic inductance detector (KID) to enable high multiplexing factors. The spectrometer is fabricated using stacks of silicon wafers etched with a deep reactive-ion etch (DRIE) and metallized. In these proceedings, we discuss current development on a SWISS prototype including measurements on a prototype antenna front end contactless transition and fabrication a prototype waveguide spectrometer.

astro-ph.IM↗

arXiv2024

A first demonstration of active feedback control and multi-frequency imaging techniques for kinetic inductance detectors

RF-ICE is a signal processing platform for the readout of large arrays of superconducting resonators. Designed for flexibility, the system's low digital latency and ability to independently and dynamically set the frequency and amplitude of probe tones in real time has enabled previously-inaccessible views of resonator behaviour, and opened the door to novel resonator control schemes. We introduce a multi-frequency imaging technique, developed with RF-ICE, which allows simultaneous observation of the entire resonance bandwidth. We demonstrate the use of this technique in the examination of the response of superconducting resonators to variations in applied readout current and thermal loading. We observe that, used in conjunction with a conventional frequency sweep at sufficiently large amplitude to induce resonance bifurcation, the multi-frequency imaging technique reveals a resonator response which is not captured by the frequency sweep measurement alone. We demonstrate that equivalent resonant frequency shifts can be achieved using either thermal, optical, or readout loading, and use this equivalence to counteract a change in thermal loading by digitally modulating the readout current through a resonator. We develop and implement a proof-of-concept closed-loop negative electro-quasiparticle feedback algorithm which first sets and then maintains the resonant frequency of a lumped element kinetic inductance detector while the loading on it is varied. Although this simple implementation is not yet suitable to deploy at scale, it demonstrates the utility of this feedback technique to improve linearity while addressing amplifier distortion, resonator response non-uniformity, and crosstalk. It can be applied to kinetic inductors in non-bolometric operation, and sets the stage for future developments.

astro-ph.IM↗

arXiv2021

Development of MKIDs for measurement of the Cosmic Microwave Background with the South Pole Telescope

We present details of the design, simulation, and initial test results of prototype detectors for the fourth-generation receiver of the South Pole Telescope (SPT). Optimized for the detection of key secondary anisotropies of the cosmic microwave background (CMB), SPT-3G+ will measure the temperature and polarization of the mm/sub-mm sky at 220, 285, and 345 GHz, beyond the peak of the CMB blackbody spectrum. The SPT-3G+ focal plane will be populated with microwave kinetic inductance detectors (MKIDs), allowing for significantly increased detector density with reduced cryogenic complexity. We present simulation-backed designs for single-color dual-polarization MKID pixels at each SPT-3G+ observation frequency. We further describe design choices made to promote resonator quality and uniformity, enabling us to maximize the available readout bandwidth. We also discuss aspects of the fabrication process that enable rapid production of these devices and present an initial dark characterization of a series of prototype devices.

astro-ph.IM↗

arXiv2020

The impact of inelastic self-interacting dark matter on the dark matter structure of a Milky Way halo

We study the effects of inelastic dark matter self-interactions on the internal structure of a simulated Milky Way (MW)-size halo. Self-interacting dark matter (SIDM) is an alternative to collisionless cold dark matter (CDM) which offers a unique solution to the problems encountered with CDM on sub-galactic scales. Although previous SIDM simulations have mainly considered elastic collisions, theoretical considerations motivate the existence of multi-state dark matter where transitions from the excited to the ground state are exothermic. In this work, we consider a self-interacting, two-state dark matter model with inelastic collisions, implemented in the Arepo code. We find that energy injection from inelastic self-interactions reduces the central density of the MW halo in a shorter timescale relative to the elastic scale, resulting in a larger core size. Inelastic collisions also isotropize the orbits, resulting in an overall lower velocity anisotropy for the inelastic MW halo. In the inner halo, the inelastic SIDM case (minor-to-major axis ratio $s \equiv c/a \approx 0.65$) is more spherical than the CDM ($s \approx 0.4$), but less spherical than the elastic SIDM case ($s \approx 0.75$). The speed distribution $f(v)$ of dark matter particles at the location of the Sun in the inelastic SIDM model shows a significant departure from the CDM model, with $f(v)$ falling more steeply at high speeds. In addition, the velocity kicks imparted during inelastic collisions produce unbound high-speed particles with velocities up to 500 km s$^{-1}$ throughout the halo. This implies that inelastic SIDM can potentially leave distinct signatures in direct detection experiments, relative to elastic SIDM and CDM.

astro-ph.GA↗

arXiv2017

Constructing Adjacency Arrays from Incidence Arrays

Graph construction, a fundamental operation in a data processing pipeline, is typically done by multiplying the incidence array representations of a graph, $\mathbf{E}_\mathrm{in}$ and $\mathbf{E}_\mathrm{out}$, to produce an adjacency array of the graph, $\mathbf{A}$, that can be processed with a variety of algorithms. This paper provides the mathematical criteria to determine if the product $\mathbf{A} = \mathbf{E}^{\sf T}_\mathrm{out}\mathbf{E}_\mathrm{in}$ will have the required structure of the adjacency array of the graph. The values in the resulting adjacency array are determined by the corresponding addition $\oplus$ and multiplication $\otimes$ operations used to perform the array multiplication. Illustrations of the various results possible from different $\oplus$ and $\otimes$ operations are provided using a small collection of popular music metadata.

cs.DS↗

arXiv2015

Algebraic Conditions for Generating Accurate Adjacency Arrays

Data processing systems impose multiple views on data as it is processed by the system. These views include spreadsheets, databases, matrices, and graphs. Associative arrays unify and simplify these different approaches into a common two-dimensional view of data. Graph construction, a fundamental operation in the data processing pipeline, is typically done by multiplying the incidence array representations of a graph, $\mathbf{E}_\mathrm{in}$ and $\mathbf{E}_\mathrm{out}$, to produce an adjacency matrix of the graph that can be processed with a variety of machine learning clustering techniques. This work focuses on establishing the mathematical criteria to ensure that the matrix product $\mathbf{E}_\mathrm{out}^\intercal\mathbf{E}_\mathrm{in}$ is the adjacency array of the graph. It will then be shown that these criteria are also necessary and sufficient for the remaining nonzero product of incidence arrays, $\mathbf{E}_\mathrm{in}^\intercal\mathbf{E}_\mathrm{out}$ to be the adjacency matrices of the reversed graph. Algebraic structures that comply with the criteria will be identified and discussed.

cs.DB↗