Development of Superconducting Parametric Amplifiers for Astrophysics Applications

  • Thomas Sweetnam

Student thesis: Phd


Superconducting parametric amplifiers are a promising technology with a wide range of applications in astronomy, particle physics and quantum technologies. The large bandwidth, high gain that they are able to achieve with added noise levels approaching the quantum limit means they provide a strong improvement over other amplifier technologies for applications requiring maximum sensitivity such as the search for the dark matter axion. This thesis aims to contribute towards this exciting research field through the development of novel techniques for the simulation, design and testing of parametric amplifiers using the kinetic inductance nonlinearity. Kinetic inductance travelling wave parametric amplifiers (KI-TWPAs) have been simulated using a novel method in Keysight's Advanced Design System. A lumped element representation of a superconducting transmission line has been developed using nonlinear inductor elements to represent the current dependency of the intrinsic kinetic inductance. This provides a fast, simple and easily modifiable method for analysing the parametric processes that occur in nonlinear kinetic inductance devices, such as parametric oscillators or amplifiers, while also allowing the accompanying RF network to be optimised. This methodology is extended and used to design resonant parametric amplifiers, that are fabricated and tested in a custom waveguide setup at cryogenic temperatures without the need for any bond wires or probes. The results of measurements of the resonator nonlinearity with temperature and power are presented and explained, and parametric gain measured in the presence of a strong pump tone. Devices containing multiple resonators are tested and the results presented, investigating the interaction between resonators in an easily modifiable system. Further investigations of parametric amplifier design and performance are performed by extending the simulation methods developed in ADS to provide information on the quantum efficiency of a TWPA. Using this, the quantum efficiency of KI-TWPA designs is explored and the results used to tailor the geometry of a KI-TWPA to improve the quantum efficiency using floquet engineering. A simple modification to amplifier designs is presented, which has the potential to significantly reduce the noise in these devices due to sideband couplings.
Date of Award1 Aug 2024
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorMark Mcculloch (Supervisor) & Lucio Piccirillo (Supervisor)


  • Keysight ADS
  • Cryogenics
  • Resonant Parametric Amplifier
  • Kinetic Inductance
  • Parametric Amplifier
  • Ansys HFSS
  • Quantum Devices
  • Superconductivity
  • Superconducting Parametric Amplifiers
  • TWPA

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