Single-photon detection using large-scale high-temperature MgB₂ sensors at 20 K.

Area of Science:

• Materials Science
• Quantum Optics
• Superconductivity

Background:

• Single-photon detectors are crucial for quantum communication, cryogenics, and medical imaging.
• Existing detectors often face limitations in operating temperature, speed, and scalability.
• Magnesium diboride (MgB2) is a promising material for superconducting applications.

Purpose of the Study:

• To demonstrate MgB2 thin-film superconducting microwires for single-photon detection.
• To investigate the performance characteristics of these detectors, including sensitivity, efficiency, and speed.
• To explore the potential for high-temperature operation and large-area detectors.

Main Methods:

• Fabrication of MgB2 thin-film superconducting microwires.
• Modification of MgB2 properties using helium ion irradiation.
• Characterization of single-photon detection capabilities at 1.55 μm wavelength.
• Measurement of detector performance metrics such as operating temperature, detection efficiency, linearity, and reset time.

Main Results:

• MgB2 microwire detectors exhibit single-photon sensitivity at 1.55 μm.
• Detectors show sensitivity up to 20 K, with efficiency saturation at 3.7 K for 1 μm wide microwires.
• Linearity of detection rate versus incident power is maintained up to 100 Mcps.
• Fast reset times of approximately 1 ns are achieved for large active areas (up to 400 × 400 μm²).

Conclusions:

• MgB2 thin-film superconducting microwires are viable for single-photon detection.
• These detectors offer potential for overcoming operating temperature and count rate limitations.
• The findings open possibilities for expanded detector areas and further research into fundamental detection mechanisms in high-critical-temperature superconductors.