Exploiting nonlinear oscillators for quantum information processing and measurement

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The main goal of the project was to develop Kerr Parametric Oscillators (KPOs). These KPOs were to be used first to generate itinerant cat states, with further goals being observation of chaotic behaviour across the quantum-classical boundary, implementing two-KPO gates, and moving towards implementations of quantum simulations using KPOs.Several generations of KPOs have been designed, fabricated, and experimentally characterized. The first generations suffered from high loss rates, rendering most of the mentioned experimental goals impossible. The device was improved each generation, and the most recent generation has properties that may allow proof-of-principle demonstrations of some of the mentioned experiments. Moreover, we know how to further improve the device characteristics for future experiments. This project has not yet lead to published results, is promising regarding future results.Besides the main project, I developed Josephson parametric amplifiers for a collaboration with an axion search team. These amplifiers will allow them to show or exclude the existence of axions in a much shorter timescale than would be possible using only conventional HEMT amplifiers. The amplifiers were tested to work, and are in current use within that project. We have so far co-authored 2 papers on this subject.I also collaborated with S. Kono on his project on developing a Josephson Quantum Filter, aiming to break the trade-off between fast control of a qubit, and the decay of that qubit due to the presence of the control line.