Circuit QED devices for probing Majorana zero modes

Abstract: Theoretical understanding indicates that Majorana zero modes in solid-state systems could be utilized for fault-tolerant quantum information processing. The ability to reliably detect these excitations, however, remains a challenge and many of their properties are still unknown. In this Master's project, devices that implement a circuit quantum electrodynamics architecture and are predicted to host Majorana zero modes have been fabricated and characterized at temperatures below 50 mK. Single-junction as well as split-junction geometries have been investigated. In neither case have the expected Majorana signatures been detected. A primary difficulty is operating the devices in magnetic fields large enough to induce the presence of Majorana zero modes. Effects in which the signatures are expected to occur, charge dispersion for the single-junction case and flux dependence for the split-junction case, have been resolved at in-plane fields of approximately 150 mT and 300 mT, respectively. Although non-affirmative of the existence of Majorana states in the devices, the results represent a step toward detection and eventually utilization of Majorana zero modes in superconducting circuits.