Student Name: Mr. Shubham Chaudhary
Date/Time: 21.08.2025 / 11:00 AM
Research Supervisor : Baladitya Suri
Venue: IAP MMCR.
Title: Characterization of Quality Factor of Superconducting Resonators.
Abstract:
Superconducting lumped element resonators play a pivotal role in circuit quantum electrodynamics (cQED) architectures, serving both as protective filters that isolate qubits from environmental noise and as sensitive probes for qubit state readout. The performance of these resonators is fundamentally limited by various loss mechanisms that arise during device fabrication and operation. Among these, dielectric loss due to parasitic two-level systems (TLSs) residing in native oxides or dielectric layers on metal and substrate surfaces is a major source of decoherence at low powers. These losses are highly dependent on device geometry, fabrication techniques, material quality, and substrate-metal interfaces. In this project, I designed and fabricated lumped element resonators with a focus on achieving high internal quality factors (Qi).
I performed a systematic study of Quality factors of these superconducting resonators by varying substrates, superconducting metals, and fabrication process. A total of four different kind of devices were fabricated using superconducting thin films and standard lithographic techniques. Each device underwent systematic optimisation of its fabrication recipe to reduce sources of loss and improve performance. Through careful design, materials selection, and fabrication process refinement, this study showed that resonators fabricated on tantalum thin film suffer the least from dielectric noise, which is the most dominant noise channel.
About the Student:
Mr. Shubham did his BTech in Biochemical Engineering from Harcourt Butler Technical University, Kanpur. He joined Quantum Technologies Lab at IISc as a MTech (Res) student in 2022.