Single-Photon Source Using Point Defects for Room-Temperature Output
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Solution Overview
Problem
Current single-photon sources for quantum cryptography communication and sensing using point defects in wide-bandgap semiconductors face challenges in efficiently extracting single photons at room temperature and preventing simultaneous emission of multiple photons, with existing methods being impractical for real-world applications due to the need for extremely low temperatures and inefficiencies in light concentration.
Innovation Solution
A single-photon source comprising a wide-bandgap semiconductor substrate with a light-emission region containing a single target point defect, a cover mask exposing the region, and an excitation system that shifts electrons from a defect-ground state to an excited state, allowing a single photon to be output through the mask opening, utilizing either photoluminescence or electroluminescence for excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-magnification lens or solid immersion lens is used to focus light from point defects, then light concentration efficiency is improved, but manufacturing complexity and difficulty increase due to special fine processing requirements
Solution Approach 1:
The patent introduces a photonic crystal as an intermediary structure between the point defect and the output interface. This photonic crystal serves as a mediator that provides both light concentration functionality and a standardized, manufacturable structure, avoiding the need for complex solid immersion lenses while achieving efficient photon extraction
Solution Approach 2:
The patent modifies the refractive index distribution and optical properties by introducing a photonic crystal structure with specific periodicity and geometry. This changes the optical parameters to achieve enhanced light extraction efficiency without requiring complex lens manufacturing, transforming the approach from conventional optics to photonic crystal-based optics
2Productivity
If conventional single-photon sources are used for quantum cryptography communication, then device availability exists, but reliability decreases due to probability of simultaneously outputting multiple photons
Solution Approach 1:
The patent confines the light emission to a highly localized region by selecting and isolating a single point defect within the photonic crystal structure. This local quality approach ensures that only one specific defect contributes to photon emission, eliminating the possibility of multiple photons from different defects being emitted simultaneously
Solution Approach 2:
The patent segments the emission process by isolating individual point defects and selecting only one for active emission. The photonic crystal structure divides and directs light from this single selected defect, ensuring that the system operates as a true single-photon source rather than a multi-photon source
3Productivity
If quantum dots are used as single-photon sources, then light concentration capability is improved, but operational temperature requirement becomes extremely low (several to several tens of kelvins)
Solution Approach 1:
The patent changes the material parameter by using wide-bandgap semiconductor materials (such as diamond, SiC, GaN) with inherent room-temperature operation characteristics. This material parameter change allows the system to maintain quantum optical properties and efficient light emission at room temperature, eliminating the need for cryogenic cooling required by quantum dot systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the stable and controlled output of single photons at room temperature, improving the efficiency of quantum cryptography communication by ensuring only one photon is emitted at a time, and facilitating practical applications by simplifying the device configuration.
Implementation Method 1
utilizing either photoluminescence or electroluminescence for excitation
Implementation Method 2
utilizing either photoluminescence or electroluminescence for excitation
Implementation Method 3
single photons emitted from a single point defect
Data Source
AI summary
A single-photon source includes a substrate of a wide-bandgap semiconductor provided with a light-emission region including only one target point detect, a cover mask arranged on a main surface of the substrate and having an opening to which the light-emission region in the substrate is exposed, and an excitation system configured to shift an electron in a defect-ground state to an excited state at the point defect in the light-emission region. A single photon released from the point defect in the light-emission region when the electron in the excited state is shifted to the ground state is output through the opening in the cover mask.