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Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies
Thesis (MEng)--Stellenbosch University, 2024.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2024
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| _version_ | 1867614071062265856 |
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| access_status_str | Open Access |
| author | Meyer, Kobus |
| author2 | Fourie, Coenrad |
| author_browse | Fourie, Coenrad Meyer, Kobus |
| author_facet | Fourie, Coenrad Meyer, Kobus |
| author_sort | Meyer, Kobus |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130472 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:46:11.731Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130472 Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies Meyer, Kobus Fourie, Coenrad Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Electric lines Superconductors Semiconductors Finite element method UCTD Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: In this thesis the frequency-dependent characteristics of superconductor transmission line discontinuities are investigated using the Finite-Difference Time-Domain (FDTD) method, and the capabilities of Josephson Travelling Wave Parametric Amplifiers (JTWPAs) are investigated in the form of a literature review and with a phase-based circuit simulation. Superconductor electronic devices are pivotal in the search for computing technologies that can overcome the limitations of CMOS. Superconductor digital logic research is an active field; current state-of-the-art logic gates can operate at tens of gigahertz at a fraction of the power used by their conventional semiconductor counterparts. In quantum computers, superconductors are used in qubit implementation, and in interface circuits which connect the very low-temperature qubits with the outside world. The integrity of very small signals is an important consideration in both quantum and superconductor computing. The FDTD method is implemented in MATLAB, and the two-fluid model of superconductivity is incorporated as a frequency-dependent conductivity using the auxiliary differential equation method. The E-field update equations are presented for both the supercurrent and the normal current. Frequency-dependent s-parameters are extracted for discontinuities in microstrip line and stripline. S21 magnitudes obtained are within 0.06 dB of results from literature, and phase velocities are within 4.4% of values from commercial superconducting solver, InductEx. A frequency-dependent lumped element circuit model is extracted for stripline bends and a via in the MIT-LL SFQ5ee process. Even when approximating the circuit as frequency invariant, the phase of the voltage wave travelling through the discontinuity is within 0.7 degrees of the FDTD result. The values of lumped element models extracted support the results obtained by measurement by Shukla et al. in 2019 for circuits fabricated in the afore mentioned process, demonstrating that RSFQ (Rapid Single Flux Quantum) logical data transmission on striplines is negatively affected by the insertion of multiple vias. AFRIKAANSE OPSOMMING: In hierdie tesis word die frekwensie-afhanklike eienskappe van supergeleier transmissielyn diskontinuiteite ondersoek by wyse van die Finite-Difference Time-Domain (FDTD) metode, en die eienskappe van Josephson Travelling Wave Parametric Amplifiers (JTWPAs) word ondersoek in die vorm van ’n literatuurstudie en fasegebaseerde stroombaansimulasie Supergeleier elektroniese toestelle is onontbeerlik in the soektog na rekenaar tegnologie¨e wat die beperkinge van CMOS kan oorkom. Supergeleidende digitale logika navorsing is ’n aktiewe navorsingsveld. Toestelle aan die voorpunt hiervan sluit in logiese bane wat teen tiene van gigahertz hardloop en ’n breukdeel van die krag wat deur hul half-geleier ewekni¨e verkwis. In kwantum rekenaars word supergeleiers gebruik in die bou van kwantum bisse of qubits, en dien as skakel in die konneksie tussen baie lae temperatuur qubits en die buitewˆereld. Die kwaliteit van baie klein seine is ’n belangrike deel van beide hierdie velde. Die FDTD simulasie metode is in MATLAB ge¨ımplementeer en die two-fluid model van supergeleiding is ingevoeg as ’n frekwensie-afhanklike geleidingsvermo¨e, deur die auxiliary differential equation metode. Die E-veld opdateringsberekeninge word afgelei vir die super-stroom en die normaal-stroom. Frekwensie-afhanklike s-parameters is onttrek vir diskontenu¨ıteite in mikrostrooklyn en strooklyn. Die grootte van S21 parameters is binne 0.06 dB van resultate vanuit die literatuur, en golfsnelhede val binne 4.4% van die waardes vanaf kommersi¨ele supergeleier veldoplosser, InductEx. ’n Frekwensie-afhanklike diskete element stroombaanmodel is onttrek vir strooklyn hoeke en ’n via in die MIT-LL SFQ5ee proses. Selfs wanneer die stroombane as frekwensieinvariant beskou word, is die fase van ’n spanningsgolf wat deur die diskontinu¨ıteit beweeg binne 0.7 grade van die FDTD resultaat. Die waardes van lumped element modelle verkry ondersteun deur die meetings deur Shukla et al. 2019 vir stroombane wat in MIT-LL SFQ5ee proses geskep is, wat bewys dat RSFQ (Rapid Single Flux Quantum) data versending negatief deur die invoeging van veevuldige vias be¨ınvloed word. Masters 2024-02-29T07:47:36Z 2024-04-26T18:51:14Z 2024-02-29T07:47:36Z 2024-04-26T18:51:14Z 2024-03 Thesis https://scholar.sun.ac.za/handle/10019.1/130472 en_ZA en_ZA Stellenbosch University xiv, 103 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Electric lines Superconductors Semiconductors Finite element method UCTD Meyer, Kobus Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title | Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title_full | Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title_fullStr | Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title_full_unstemmed | Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title_short | Extraction of frequency-dependent parameters of passive superconductor structures using the finite-difference time-domain method at sub-terahertz frequencies |
| title_sort | extraction of frequency dependent parameters of passive superconductor structures using the finite difference time domain method at sub terahertz frequencies |
| topic | Electric lines Superconductors Semiconductors Finite element method UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/130472 |
| work_keys_str_mv | AT meyerkobus extractionoffrequencydependentparametersofpassivesuperconductorstructuresusingthefinitedifferencetimedomainmethodatsubterahertzfrequencies |