Fabrication and characterization of superconducting circuit QED devices for quantum computation

TL;DR

This paper details the fabrication and characterization of superconducting circuit QED devices, including high-Q cavities and Cooper pair boxes, for advancing quantum computation through strong coupling regimes.

Contribution

It introduces new fabrication techniques and RF characterization methods for superconducting resonators and qubits, enhancing device quality and diagnostic capabilities.

Findings

Achieved high-quality factor cavities up to 10^6

Demonstrated strong coupling regime in cQED devices

Provided RF characterization of resonators under varying conditions

Abstract

We present fabrication and characterization procedures of devices for circuit quantum electrodynamics (cQED). We have made 3 GHz cavities with quality factors in the range 10^4--10^6, which allow access to the strong coupling regime of cQED. The cavities are transmission line resonators made by photolithography. They are coupled to the input and output ports via gap capacitors. An Al-based Cooper pair box is made by ebeam lithography and Dolan bridge double-angle evaporation in superconducting resonators with high quality factor. An important issue is to characterize the quality factor of the resonators. We present an RF-characterization of superconducting resonators as a function of temperature and magnetic field. We have realized different versions of the system with different box-cavity couplings by using different dielectrics and by changing the box geometry. Moreover, the cQED approach can be used as a diagnostic tool of qubit internal losses.