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Nonlinear Josephson Transmission Lines based on High-Temperature Superconductors

Alizadeh, Arman | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53528 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Rejaei, Behzad; Fardmanesh, Mehdi
  7. Abstract:
  8. Metamaterials are engineered sub-wavelength structures which show electromagnetic properties not found in natural materials. There is a special interest in superconductor metamaterials in microwave engineering. These metamaterials have low loss, are compact and show useful properties like tunability and parametric amplification when Josephson junctions are incorporated in them. When Josephson junctions are used, these metamaterials are called Josephson metamaterials which have attracted a good amount of research interest. Because of nonlinear nature of Josephson junction, Josephson metamaterials show nonlinear properties. One dimensional Josephson metamaterials are called Josephson transmission lines and divided into Right-Handed (RH) and Left-Handed (LH) types. RH types are used in parametric amplifiers which are essential in today’s quantum computers. But LH types have never been studied substantially which has encouraged us to explore their theory and design in this thesis. A special kind of Josephson junction called Step-Edge Josephson junction (SEJ) has been considered in cases of design of an actual layout which is a High-Temperature Superconductivity (HTS) technology.A Josephson Left-Handed Transmission Line (JLHTL) based on SEJs has been designed. Two stop-bands of this JLHTL are tunable by bias current of Josephson junction arrays. The monolayer layout design allows independent bias of unitcells which is intended for the compensation of inhomogeneity in the fabrication process of SEJ arrays. Besides this is a unique and essential property that can be useful in digital metamaterials.
    Then we investigate parametric amplification of two waves which are called Stokes and Anti-Stokes waves in optical nonlinear materials, for the first time in a JLHTL. We show that the results of simulations is in good agreement with the theoretical prediction that we have made for the frequencies of these two waves. This type of parametric amplification can be used to compensate for high-frequency losses in Josephson metamaterials.
    We also address the probabilistic analysis of tunability in Josephson junction arrays when inhomogeneity in fabrication process is present. We quantitatively describe the reduction of tunability factor in the arrays which can be useful to successfully predict the quality of tunability of JLHTLs in HTS technology
  9. Keywords:
  10. Josephson Junction ; High Temperature Superconductor ; Parametric Amplification ; Superconducting Metamaterials ; Left-Handed Transmission Lines

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