Developing Phase Slip Fluxonium Qubits
Abstract: The Josephson junction (JJ) is an essential component of superconducting qubits. They provide nonlinearity in transmon qubits and allow for tunneling of the energy barrier in fluxonium qubits. However, aluminum-based JJs have a low Tc (1.2 K), limiting the operating temperature to << 1 K and the frequency range of photons to << 70 GHz. In this talk, I will introduce thin films of disordered superconducting wires as an alternative to JJs. These disordered films have large intrinsic quality factors and thus could potentially lead to high coherence in superconducting qubits. I will focus on thin films made of titanium nitride (TiN), which relative to aluminum, has a large superconducting gap, allowing for a wider range in operating temperature and frequency space. Furthermore, I will demonstrate how JJs could be replaced in both the superinductance and phase slip components of the fluxonium qubit through the kinetic inductance and the phase slip phenomena in nanowires. Finally, I will describe our experimental progress in characterizing the quality of our TiN film and the nonlinearity of our superconducting nanowires.