Development of Cryogenic Thermal Sensors Based on Silicon Diodes for the Control Interface of Superconducting Qubits.

• Grant number: 25/15957-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Engineering - Electrical Engineering - Electrical Materials
• Principal Investigator: Marcos Vinicius Puydinger dos Santos
• Grantee: Paulo Gonçalves Serra Neto
• Host Institution: Faculdade de Engenharia Elétrica e de Computação (FEEC). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 24/00998-6 - Center for Research and Innovation on Smart and Quantum Materials (CRISQuaM), AP.CEPID

Abstract

Quantum computing emerges as a new paradigm in the face of the limitations of Moore's Law. Superconducting qubits, a promising platform for this technology, require operation at cryogenic temperatures (typically on the order of 0.01 K), where thermal fluctuations are a critical source of errors that degrade quantum coherence. The scalability of these systems is limited by the bottleneck of the quantum-classical interface, driving the development of Cryo-CMOS control electronics, which operate in 1-4 K stages. In this context, precise thermometry integrated into the chips where the qubits reside is essential for the stability and diagnostics of the entire system.In this sense, this project proposes the fabrication and characterization of silicon diodes as cryogenic thermal sensors for this interface. PN homojunction and Schottky barrier (metal-semiconductor) diodes will be developed and compared, fabricated using microfabrication techniques at CCSNano/Unicamp. The electrical characterization, performed in the cryogenic environment of IFGW/Unicamp, will allow us to evaluate the sensitivity of these devices, their detection limits, and their response to static and variable magnetic fields. The goal is to develop a low-cost solution that can potentially be integrated with superconducting qubits, contributing an essential instrumentation technology for the advancement of quantum computing in Brazil.