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Current crowding-free superconducting nanowire single-photon detectors
Stefan Strohauer1,2, Fabian Wietschorke1,3, Christian Schmid1,3
1Walter Schottky Institute, Technical University of Munich, 85748 Garching, Germany.
Science Advances
|March 28, 2025
Summary
Researchers developed a new method to improve single-photon detector performance. By selectively irradiating superconducting nanowire single-photon detectors (SNSPDs), they reduced current crowding, leading to enhanced sensitivity and lower dark count rates for critical applications.
Area of Science:
- Quantum optics and photonics
- Superconducting device physics
Background:
- Single-photon detection is crucial for quantum science, dark matter research, and biomedical imaging.
- Superconducting nanowire single-photon detectors (SNSPDs) offer high efficiency and low noise but are limited by current crowding in their bends.
- Current crowding degrades SNSPD performance metrics like detection efficiency and timing jitter.
Purpose of the Study:
- To mitigate performance limitations in SNSPDs caused by current crowding.
- To enhance SNSPD sensitivity and reduce dark count rates through targeted irradiation.
- To enable efficient single-photon detection with improved operational parameters.
Main Methods:
- Developed a localized helium ion irradiation technique for SNSPDs.
- Irradiated only the straight segments of meander-shaped SNSPDs, leaving the bends unirradiated.
- Quantified performance improvements by measuring saturation plateau width, internal detection efficiency, and dark count rate.
Main Results:
- Locally irradiated SNSPDs exhibited a relative saturation plateau width of 37%, significantly higher than fully irradiated detectors (10%).
- This wider plateau allows operation at lower bias currents, reducing dark count rates while maintaining high detection efficiency.
- Achieved an internal detection efficiency of 94% with a dark count rate of 7 mHz at 780 nm.
Conclusions:
- Localized irradiation is an effective strategy to overcome current crowding in SNSPDs.
- The developed method enhances SNSPD sensitivity and reduces dark count rates, improving detector performance.
- These current crowding-free SNSPDs are well-suited for demanding applications requiring precise single-photon detection.
