China Begins Mass Production of Photon Detectors to Power Quantum Radars Capable of Tracking Advanced Stealth Fighters

China has reportedly begun mass production of an ultra-low-noise, four-channel single-photon detector, a device that its state media claims could become the backbone of future quantum radar systems capable of detecting and tracking advanced stealth aircraft. The announcement, made by Beijing’s quantum technology research division, marks a significant milestone in the global race toward developing next-generation radar systems that operate at the edge of quantum physics.

What Exactly Is a Photon Detector?

A photon detector is a highly sensitive optical sensor designed to register and count individual photons — the smallest particles of light. Unlike conventional photodetectors, which require a strong light signal to function, single-photon detectors (SPDs) can detect even a single photon with remarkable precision.

These detectors are usually built using superconducting nanowire single-photon detectors (SNSPDs) or single-photon avalanche diodes (SPADs). SNSPDs offer the highest detection efficiency and extremely low noise but must operate at cryogenic temperatures, often close to absolute zero. The new Chinese device reportedly operates with “ultra-low noise” across four independent channels, suggesting a design optimized for both sensitivity and scalability.

By integrating four detection channels into one compact module, Chinese engineers claim the device can process multiple photon streams simultaneously, paving the way for higher-resolution imaging and faster data collection — critical requirements for quantum radar and quantum LiDAR applications.

How Quantum Radar Could Track Stealth Fighters

The core concept behind quantum radar lies in quantum illumination, a technique that uses pairs of correlated photons. One photon from each pair — known as the signal photon — is sent toward a target area, while its partner, the idler photon, is retained.

When the signal photon bounces off a potential target and returns, it can be matched with its idler counterpart through quantum correlation. This allows the system to extract faint signals from background noise — even if the reflected photon has lost its original quantum entanglement due to atmospheric effects.

This capability could, in theory, allow quantum radars to detect stealth aircraft, which are designed to minimize radar reflections at traditional microwave frequencies. Since quantum radars may operate in optical or microwave quantum bands, their detection principle differs entirely from conventional radar, relying on photon correlation rather than radio-wave strength.

If achieved, this would make it possible to “see” low-observable aircraft — such as the F-22 Raptor, F-35 Lightning II, or China’s own J-20 — even in cluttered or noisy environments.

Technical Challenges Still Stand in the Way

Despite the theoretical advantages, quantum radar remains far from operational deployment. The challenges include:

• Atmospheric interference: Quantum signals are fragile, and even small amounts of dust, humidity, or turbulence can destroy photon correlations.

• Cooling requirements: The best photon detectors, such as SNSPDs, must operate at temperatures below 3 Kelvin (–270°C), demanding bulky cryogenic cooling systems that limit portability.

• Power and range trade-offs: Most laboratory quantum radars operate over a few meters to a few kilometers at best, far short of the hundreds of kilometers needed for military-grade air defense.

• Data processing: Quantum radar requires massive computational power to analyze and correlate photon data in real time, another major engineering hurdle.

Thus, while China’s mass production of photon detectors represents an important industrial step, it doesn’t automatically mean quantum radars are ready to track stealth aircraft across large distances. The technology is still in its experimental phase worldwide.

Global Race: Who Else Is Developing Photon Detectors and Quantum Radars

China is not alone in this pursuit. The United States, Europe, India, and Russia are all advancing their own quantum sensing programs:

• United States: The Defense Advanced Research Projects Agency (DARPA) has been funding several initiatives under its “Quantum Apertures” and “Robust Quantum Sensors” programs. U.S. defense contractors and universities have tested quantum-enhanced microwave sensors that operate on similar principles.

• Europe: Countries such as the United Kingdom, France, and Germany are investing in quantum LiDAR and photon detection technologies, primarily for scientific and civilian applications but with clear dual-use potential.

• Russia: Research institutes in Moscow and St. Petersburg are conducting theoretical studies and prototype work on quantum communication and sensing.

• India: India’s National Mission on Quantum Technologies & Applications (NM-QTA) includes research on quantum sensors, secure communications, and cryogenic photon detectors, though it remains in the early development stage.

Many of these programs are focused not only on radar but also on quantum communications, navigation, and imaging, fields where single-photon detectors are equally crucial.

Why China’s Announcement Matters

Mass-producing a four-channel, ultra-low-noise photon detector could make China one of the first nations to bring such sensors out of the laboratory and into industrial-scale manufacturing. This could accelerate development not only in quantum radar but also in quantum communication networks, space-based sensing, and autonomous navigation systems that rely on photon-level precision.

Still, experts caution that mass production of detectors is only one step in a long technological chain. Turning them into a fully operational quantum radar requires breakthroughs in quantum signal generation, long-range coherence management, and real-time correlation processing.

In simple terms, China may have built a better “eye,” but the rest of the body — the radar platform, processing algorithms, and operational integration — still needs to catch up.

A Step Closer, But Not There Yet

The production of photon detectors marks genuine progress in quantum sensing hardware, but it does not mean stealth technology has been defeated. Theoretical predictions suggest that quantum radar advantages might become meaningful only under specific conditions, such as short-range detection or low-noise environments.

Nevertheless, this development signals a clear intent from Beijing to industrialize quantum technologies that were, until recently, confined to research laboratories. For now, the world’s air forces can continue relying on stealth — but the age of quantum-enhanced sensing may be closer than ever.