Instituição de defesa: CBPF - Centro Brasileiro de Pesquisas Físicas

Resumo: This Thesis explores methods to enhance the reproducibility of Josephson junctions, crucial elements in superconducting quantum technologies, when employing the Dolan technique in 30 kV e-beam processes. The study explores the influence of dose distribution along the bridge area on reproducibility, addressing challenges related to fabrication sensitivity. Experimental methods include E-beam lithography, with electron trajectory simulations shedding light on backscattered electron behavior. We describe the fabrication of various Josephson junction geometries and analyze the correlation between the success rates of different lithography patterns and the simulated distribution of backscattered electrons. Our findings demonstrate a success rate of up to 96.3% for the double resist 1-step low-energy e-beam lithography process. As a means of implementation strategy, we provided a geometric example that takes advantage of simulated stability regions to administer a controlled, uniform dose across the junction area, introducing novel features to overcome the difficulties associated with fabricating bridge-like structures. Furthermore we also explore the fabrication of superconducting circuits through thin film deposition and subsequent etching, also known as "Top Down" method. The thin films studied were Nb and Al, they were tested with various reagents and for many applications, allowing us to define configuration which can best be used for superconducting circuit fabrication. Furthermore we employ the techniques developed into a working Transmon device. We observe cavity dressed and bare mode, demonstrating an effective means of developing Josephson junction based superconducting quantum devices.

Área:

Data da defesa: 09/05/2024

Banca: Maycon Motta; Clodoaldo Irineu Levartoshi de Araujo