Fabry-Perot cavities for sensitivity enhancement in microwave Rydberg receivers

• Grant number: 25/19789-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2026
• End date: December 31, 2026
• Field of knowledge: Engineering - Electrical Engineering - Telecommunications
• Principal Investigator: Vinicius Marrara Pepino
• Grantee: Mateus Francisco Balesteros Cintra
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 24/12912-9 - Rydberg atoms for quantum technologies, AP.R

Abstract

This project proposes the study and implementation of a Fabry-Perot (FP) cavity to enhance the sensitivity of microwave receivers based on Rydberg atoms. These recei- vers are considered highly promising, as Rydberg states exhibit a pronounced response to electric fields across frequencies ranging from MHz to THz, enabling the detection of radiofrequency and microwave signals with high sensitivity. Their operation relies on Elec- tromagnetically Induced Transparency (EIT), a quantum-optical spectroscopy technique. The FP cavity functions to locally amplify the electric field through the constructive inter- ference of reflected waves, resulting in improved detection sensitivity. The work, linked to the research project "Rydberg Atoms for Quantum Technologies", will be developed in synergy between the São Carlos School of Engineering (EESC) and the Institute of Physics of São Carlos (IFSC/USP), with the goal of designing, fabricating, and validating cavity geometries capable of delivering performance comparable to or exceeding results reported in the literature. Simulations will be carried out using Ansys HFSS, preceded by a literature review on quantum receivers and microwave confinement techniques. An initial slit-based structure tuned to 9.77 GHz achieved a gain of approximately 11.7 dB with polarization selectivity, while polarization-insensitive geometries showed promising per- formance, with gains of up to 9.1 dB at 9.75 GHz. The project will provide the student with training in electromagnetic simulation methods, resonant structure analysis, and critical literature review, in addition to hands-on experience with microwave and atomic physics se- tups, contributing to their education in instrumentation for quantum microwave detection. (AU)