Design and Fabrication of a Kinetic Inductance Parameric Amplifier for multi-mode entanglement studies

Sammanfattning: Parametric amplifiers are essential for analyzing and measuring the weak signals generated byquantum circuits at cryogenic temperatures. This project aims to realize a low noise travelingwave parametric amplifier (TWPA) by exploiting the nonlinear current dependence of thekinetic inductance of superconducting NbTiN nanowires. We fabricate an inductor in theform of a compact meandering nanostructure on small chips. We describe the microwavecircuit design, the simulations performed and the fabrication recipes. We present the resultsfrom the initial measurements at low-temperature (4.2 K - 0.3 K) performed in a 3He dipstickcryostat.We analyzed two different structures in this thesis. The first design implements a co-planarwaveguide structure that operates as a multi-modal cavity with resonances that can be modifiedby adjusting geometrical parameters. In contrast, the second design attempts to eliminate theseresonances by matching the impedance of the device with that of the input and output signallines. For this reason, we adopted a microstrip structure with a top-layered ground plane.In addition, the second design allows for phase matching of the signal and idler frequenciesinvolved in parametric amplification through dispersion engineering. Finally, we determineimportant parameters like the temperature dependence of the kinetic inductance, phase velocity,and characteristic impedance of the devices at cryogenic temperatures.