Scalable Super-Localization Optical Probing of Individual Josephson Junctions in Superconducting Devices

Area of Science:

• Quantum Engineering
• Materials Science
• Metrology

Background:

• Accurate characterization of individual Josephson junctions (JJs) is crucial for superconducting devices.
• Conventional electrical methods struggle with noise and lack single-junction resolution in large arrays.

Purpose of the Study:

• To develop a noninvasive optical modulation technique for precise and selective probing of individual JJ characteristics.
• To overcome limitations of conventional electrical characterization methods.

Main Methods:

• Utilizing high-frequency (50 kHz) optical intensity modulation to alter JJ properties.
• Employing lock-in detection for precise extraction of critical current (Ic).
• Implementing beam steering or multiplexed illumination for scalable, superlocalized mapping.

Main Results:

• Achieved 1% accuracy in Ic extraction with only 100 ms integration time.
• Demonstrated comparable precision to conventional methods but with significantly reduced acquisition time.
• Enabled identification of local inhomogeneities and defects in JJ arrays.

Conclusions:

• The optical modulation technique provides an efficient, noninvasive, and scalable solution for individual JJ characterization.
• This method is applicable to precision metrology, THz sources, quantum computing, and probing novel quantum materials.