Self-contained automatic recorder of the dc Josephson current

Area of Science:

• Solid State Physics
• Superconductivity
• Electrical Engineering

Background:

• The measurement of dc Josephson current as a function of external variables like magnetic field is crucial for understanding superconducting devices.
• Previous methods often required complex signal processing, limiting their practicality and accessibility.

Purpose of the Study:

• To design and construct a novel circuit for the automatic recording of dc Josephson current.
• To develop a measurement system that simplifies the process and enhances sensitivity.

Main Methods:

• A dedicated circuit was engineered for direct recording of dc Josephson current.
• The apparatus integrates magnetic field or other variable input for automated data acquisition.
• No external signal processing units are necessary, unlike prior techniques.

Main Results:

• The circuit successfully achieved automatic recording of dc Josephson current versus magnetic field.
• High sensitivity was demonstrated, detecting critical current amplitudes that produce 5 mV across a sensing resistor.
• The system allows for separate analysis of positive and negative halves of the zero-bias current.

Conclusions:

• The developed circuit provides a simplified and effective method for measuring dc Josephson current characteristics.
• This apparatus enhances the study of superconductivity by offering improved sensitivity and direct recording capabilities.