Topological phases of matter have excitations with exotic quantum statistics and have been proposed as a platform for robust quantum computation. In this talk, I will discuss prospects for using the fluxonium artificial atom as a detector for topological phases and also as building block for topological materials.
First, I will detail our results building a nanowire-based fluxonium. Multiple transport experiments have suggested the presence of Majorana zero modes (MZM) in superconductor-proximitized nanowires but the energy scales and lifetimes associated with these states remain unknown. Coupling a fluxonium to these modes would provide access to the parity lifetime of the MZMs. Building such a device, however, requires adapting the typically aluminum-based fluxonium to incorporate nanowire-based junctions and to be resilient to high magnetic fields. We demonstrate operation of such a device and use it to investigate the behavior of a semiconducting junction up to fields of 1T.
The second part of my talk will focus on using the fluxonium to build novel quantum materials. Building a topological material from the bottom-up requires individual components with degenerate ground states and strong coupling between these components. I will present two fluxonium-based circuits: an artificial molecule with strong coupling σzσz and a circuit which realizes a cos 2φ term. Taken together, these circuits fulfill the requirements for the building blocks of topological phases. We find excellent agreement between the measured spectroscopy of the circuit and the theoretically-predicted level transitions, which highlights the suitability of superconducting circuits for implementing tailored quantum systems.
