hBN Cavity-Enhanced Single-Photon Source with Room-Temperature Operation

Novel single-photon source through integration of ultra-thin hBN membranes into fiber-based Fabry-Pérot cavities. Achieves 100-fold spectral enhancement at room temperature and eliminates costly cryogenic infrastructure for quantum communication and photonic quantum computers.

• Room-temperature operation (300 K) eliminates cryogenic infrastructure with 10-30× cost advantage
• 100-fold Spectral narrowing by factor 160 through cavity coupling
• Brightness rate 4-7 × 10⁶ counts/s with Purcell enhancement
• Integration with silicon nitride waveguides and photonic circuits
• Field-deployable for QKD networks and mobile quantum sensors
• Scalable manufacturing through 2D material platform

Quantum Communication and QKD Infrastructure: Field-deployable single-photon sources for telecommunications networks (Deutsche Telekom National Quantum Network, EuroQCI), satellite quantum communications, distributed QKD networks without cryogenic infrastructure.

Photonic Quantum Computing Components: On-chip qubit sources for photonic quantum computers (PsiQuantum wafer-scale manufacturing at GlobalFoundries, Xanadu Aurora universal photonic quantum computer). Deterministic single-photon sources as critical components for scaling to utility-scale systems (~10⁶ sources per machine).

Quantum Sensing and Imaging: Quantum radar, quantum LIDAR, biomedical magnetometry, single-spin detection. Room-temperature operation enables mobile sensor deployments and automotive integration for navigation and defense applications.

Single-photon sources are critical components for quantum communication, photonic quantum computers, and quantum sensors. However, existing quantum dot systems require dilution refrigerators at millikelvin temperatures with total costs of €750,000-€2,500,000 over 5 years. Hexagonal boron nitride (hBN) has emerged as a promising 2D material with optically active defects that can function as single-photon emitters. Integration of these emitters into photonic structures has been limited by material-induced scattering effects.

Commercial quantum applications require high-purity, bright single-photon sources that can operate at room temperature. Cryogenic systems are too expensive and complex for field deployment in telecommunications networks or mobile quantum sensors. While previous hBN quantum emitters showed room-temperature operation, they did not achieve the required spectral purity and brightness for practical applications. Integration into optomechanical cavities failed due to scattered light problems from the hBN material.

The invention comprises a systematic methodology for extracting membrane-like thin hBN structures (27-100 nm thickness) containing spectrally narrow single-photon emitters. These membranes are integrated into open fiber-based cavities using nanomanipulative techniques. The membrane thickness is below one-tenth of the emission wavelength, minimizing scattering effects. Through cavity coupling, a 100-fold spectral enhancement and 160-fold spectral narrowing are achieved at full room-temperature operation. This approach overcomes the material-induced limitation for the first time and enables the use of high-quality hBN quantum emitters in practical optomechanical systems.

P. Maier et al., arXiv 2025, Coupling of single-photon emitters in hexagonal boron nitride membranes to fiber-based Fabry-Pérot microcavities (Manuscript in preparation)

Maier, Patrick,  Kubanek, Alexander. (2025). Extracting Membrane-like hexagonal Boron Nitride hosting single Defect Centers for Resonator Integration. 10.48550/arXiv.2508.13985.