Enhancing Signal Purity in Josephson Structure Measurements

Superconducting Josephson structures play a significant role in quantum‐state engineering. Achieving high‐fidelity quantum state measurements in superconducting Josephson structures requires ultra‐low noise environments and robust signal purification techniques. Here, the advanced low‐noise signal measurement system designed for dilution refrigerators is presented, integrating multi‐stage cryogenic filtering and electromagnetic shielding strategies to suppress noise sources across a broad frequency spectrum. The effectiveness of low‐pass RC filters is demonstrated, silver‐epoxy microwave absorbers, and optimized ground isolation to achieve an unprecedented noise reduction, enabling sub‐nanoampere switching current distribution measurements superior to commerical systems at mK temperatures. The system is optimized for precision studies of superconductor‐insulator‐superconductor, superconductor‐ferromagnet‐superconductor, and superconductor‐normal metal‐superconductor Josephson junctions with low critical currents. This approach establishes a reliable framework for next‐generation quantum electronic experiments, ensuring that observed switching phenomena are governed by intrinsic device physics rather than environmental perturbations.