Towards a 2D Tantalum Kerr-Cat Qubit

Abstract

The coherence times of 2D superconducting qubits have been increased significantly by using tantalum as the main superconductor. This opens doors to 2D realization of qubits which have traditionally been made with low-loss 3D architecture. One candidate for conversion to 2D is the Kerr-cat qubit - a noise-biased qubit which exponentially suppresses phase flip by encoding the logical states into cat states of a capacitively shunted flux qubit in a 3D cavity. In this thesis, we design and fabricate a Kerr-cat qubit on our 2D tantalum platform, characterize its spectrum and unencoded coherence times, and study the effects of the encoding two-photon squeezing drive by correlating spectral properties to observed features in Rabi oscillation. Numerical simulations based on measured parameters predict cat-state behaviors and provide a benchmark for future demonstration of cat states.