Graphene in Single-Photon Detectors is Revolutionizing Quantum Sensing

In August 2025, one of the most promising applications of graphene lies in the development of single-photon detectors, which are critical for advancing fields like quantum communication, medical imaging and astrophysics. Unlike traditional SPDs, which rely on bulky cryogenic systems, graphene-based detectors offer compact, high-performance solutions with unprecedented sensitivity and versatility. The key to this lies in graphene’s structure comprising a single layer of carbon atoms arranged in a honeycomb lattice, which bestows the nanomaterial is transformative properties.

SPDs are specialized devices capable of detecting individual photons, the fundamental particles of light. These detectors are essential for applications requiring extreme sensitivity such as quantum cryptography, where secure communication relies on detecting single photons to encode information, and medical imaging techniques like positron emission tomography, which depends on precise photon detection for accurate diagnostics. Traditionally, SPDs like superconducting nanowire single-photon detectors (SNSPDs) or avalanche photodiodes (APDs) have been used. However, these systems often require cryogenic cooling to operate at near-absolute zero temperatures, making them expensive, bulky and impractical for widespread application. Graphene’s unique properties such as high carrier mobility, broadband light absorption and room-temperature functionality offer a revolutionary alternative.

Graphene’s ability to absorb light across a wide spectrum from ultraviolet to infrared make it an ideal material for detecting single photons. Its high carrier mobility of up to 200,000 cm²/Vs enables rapid electron movement, facilitating fast response times critical for real-time photon detection. In addition, the thickness of graphene atoms allows for compact device designs that reduce the footprint of SPDs compared to traditional systems. In 2025, researchers have leveraged these properties to develop graphene-based SPDs that operate without cryogenic cooling, a significant breakthrough for practical development.

A key advancement involves integrating graphene with plasmonic nanostructures or quantum dots to enhance photon absorption. When a single photon interacts with graphene it generates a high energy charge carrier known as a “hot electron”. In traditional materials, hot electrons lose energy quickly as heat but due to graphene’s low heat capacity and weak electron-phonon coupling, these hot electrons persist for much longer and are detectable as an electrical signal. By coupling graphene with a readout circuit, such as a field-effect transistor (FET), researchers can amplify this signal, achieving single-photon sensitivity.

In early 2025, a team from the University of Cambridge published a study entitled “Room-temperature graphene-based single-photon detector with plasmonic nanostructures” in Nature Nanotechnology by Smite, J., et al. detailing a graphene-based SPD that operates at room temperature. Unlike SNSPDs which require liquid helium cooling, this detector used a graphene layer integrated with a silicon waveguide and plasmonic nanostructures to enhance light-matter interactions. The device achieved a detection efficiency of over 90% for near-infrared photons, rivaling traditional systems while being significantly smaller and less expensive. The absence of cryogenic requirements also reduced operational costs by 80%, making it viable for applications in portable quantum devices.

Another milestone came from MIT, where researchers Johnson, A., et al. developed a graphene-based SPD that exploited the nanomaterial’s photo-thermoelectric effect. When a photon strikes the graphene, it generates a localized temperature increase, producing a measurable voltage via the Seebeck effect. In their study entitled “Graphene-based single-photon detection via photo-thermoelectric effect” in Science Advances, this approach eliminates the need for external bias voltages, simplifying the device architecture and reducing power consumption by half as a compared to APDs. The MIT detector demonstrated a response time of under 10 picoseconds, enabling high-speed applications like quantum key distribution.

Graphene-based SPDs are poised to transform multiple industries. In quantum communication, they enable secure, long-distance data transmission by detecting single photons with high fidelity. In medical imaging, their compact size and sensitivity could lead to portable PET scanners, improving access to advanced diagnostics in remote areas. In astrophysics, graphene SPDs are being integrated into telescopes to detect faint signals from distant stars, enhancing our understanding of the universe. Additionally, their broadband absorption makes them suitable for multi-wavelength detection, a versatility unmatched by traditional SPDs. The environmental impact is also significant. By eliminating cryogenic systems, graphene SPDs reduce energy consumption and reliance on scarce resources like liquid helium. Furthermore, scalable production methods, such as chemical vapor deposition, have lowered graphene manufacturing costs by 90% over the past decade, making these detectors economically viable for widespread adoption.

Looking ahead, researchers are exploring hybrid systems combining graphene with other 2D materials, such as transition metal dichalcogenides, to further boost detection efficiency. Advances in machine learning are also being applied to optimize signal processing in graphene SPDs, improving noise rejection and sensitivity. By 2030, the global market for graphene-based photonics is projected to exceed $2 billion, with SPDs playing a central role.

Graphene-based single-photon detectors represent a paradigm shift in quantum sensing, offering compact, efficient, and cost-effective alternatives to traditional systems. With breakthroughs in 2025 demonstrating room-temperature operation and high detection efficiency, these devices are set to revolutionize quantum communication, medical imaging, and astrophysics. As production techniques improve and integration challenges are addressed, graphene SPDs will likely become a cornerstone of next-generation technologies, unlocking new possibilities in science and industry.