Single photon detection system for visible and infrared spectrum range.

Area of Science:

• Quantum optics
• Materials science
• Photonics

Background:

• Superconducting single-photon detectors (SSPDs) are crucial for quantum information processing and low-light imaging.
• Existing SSPDs often have limited spectral sensitivity, requiring specialized detectors for different wavelength ranges.
• Niobium nitride (NbN) is a well-established material for fabricating SSPDs due to its superconducting properties.

Purpose of the Study:

• To demonstrate niobium nitride (NbN) based superconducting single-photon detectors (SSPDs) with broad spectral sensitivity.
• To evaluate the performance of these NbN SSPDs in a realistic experimental setup.
• To assess the detector's efficiency and signal-to-noise ratio across a wide spectral range.

Main Methods:

• Fabrication of NbN superconducting films and devices.
• Characterization of detector sensitivity in the visible to near-infrared spectral range (452-2300 nm).
• System performance testing using correlated photons from spontaneous parametric down-conversion (SPDC).

Main Results:

• The NbN SSPDs exhibited sensitivity across the 452-2300 nm spectral range.
• A high signal-to-noise ratio (SNR) of up to 4×10^4 was achieved.
• Photon detection efficiency (PDE) reached 64% at 1550 nm and 15% at 2300 nm.

Conclusions:

• NbN-based SSPDs offer a viable solution for broadband single-photon detection.
• The demonstrated system is suitable for applications requiring detection in both visible and infrared spectra.
• The high SNR and PDE highlight the potential of these detectors for advanced optical measurements.