Quasi-deterministic Single-Photon Source Using Heralded Frequency Conversion
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Solution Overview
Problem
Existing technologies for on-demand single-photon sources are inefficient and resource-intensive, and existing technologies have not addressed the challenges of effectively generating and distributing single-photon sources.
Innovation Solution
The proposed solution is a quasi-deterministic single-photon source that uses a photon pair generation means for generating a narrowband heralding photon with frequency f i and a narrowband heralded photon with frequency f s as a frequency-correlated photon pair upon irradiation with a pulse of pump light, using a single-photon spectrometer and a pulse shaper arrangement to reshape and convert the heralded photon into a single output photon with deterministic source frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid-state single-photon sources (N-V centers, color centers, quantum dots) are used to achieve reliable single-photon emission, then emission reliability is improved, but environmental control complexity and resource consumption increase
Solution Approach 1:
The patent uses a heralding photon as a copy or indicator of the presence of the target single photon. By detecting the heralding photon (which is easier to detect and has known properties), the system indirectly confirms the generation of the target photon without requiring direct observation or complex environmental control of the target photon source itself.
Solution Approach 2:
The heralding photon acts as an intermediary between the pump pulse and the target single photon. It carries information about the photon pair generation event and enables indirect verification of target photon creation, thereby reducing the need for complex direct monitoring and control systems.
2Ease of operation
If probabilistic heralded single-photon sources are used to simplify source operation, then ease of operation is improved, but single-photon emission certainty deteriorates
Solution Approach 1:
The detection of the heralding photon provides immediate feedback about the successful generation of a photon pair. This feedback mechanism allows the system to know when a target single photon has been created, transforming a probabilistic process into a controllable, on-demand source while maintaining operational simplicity.
Solution Approach 2:
The system uses its own byproduct (the heralding photon) to monitor and control the generation process. The heralding photon automatically provides information about successful photon pair creation, enabling self-verification and self-regulation without external intervention.
3Reliability
If multiple individual heralded single-photon sources are time-multiplexed to achieve quasi-deterministic emission, then emission reliability is improved, but device complexity and resource requirements increase
Solution Approach 1:
The patent segments the broad spectral bandwidth into multiple frequency bins, with each bin acting as an independent virtual source. This segmentation in frequency space replaces the need for segmentation in physical space (multiple separate sources), achieving the same diversification effect with a single integrated system.
Solution Approach 2:
Instead of multiplying sources in the spatial dimension (using multiple physical sources), the patent transitions to the frequency dimension, where multiple frequency bins provide the equivalent diversity. This dimensional transformation reduces physical complexity while maintaining the statistical benefits of multiple independent sources.
4Device complexity
If frequency multiplexing is used to reduce the number of laser sources, then device complexity is reduced, but switching loss scaling worsens
Solution Approach 1:
The patent eliminates the need for switching between different laser sources by using a single continuous broadband source that covers all frequency bins simultaneously. This continuous availability of all frequency components removes the switching action entirely, preventing the associated losses and scaling problems.
Solution Approach 2:
A single broadband laser source performs the function of multiple narrowband laser sources by providing all necessary frequency components simultaneously. This universal source can serve any frequency bin without requiring physical switching or multiple specialized sources, reducing both complexity and loss.
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
The solution achieves high emission probability of single photons with less resource intensity, allowing for wavelength tunability and stability against environmental drifts, with high repetition rates and indistinguishable output photons across multiple sources.
Implementation Method 1
These heralded photon sources exploit the fact that pairs of correlated photons are produced spontaneously in certain nonlinear optical interactions under a strong pump, for example in spontaneous parametric down-conversion in which a fission event of pump photons creates two lower-energy photons.
Implementation Method 2
the pulse shaper arrangement is configured for receiving output signals generated by the single-photon spectrometer, and for selecting and transmitting only frequency components f sel of the broadband pulse that substantially coincide with the frequency of the detected heralding photon
Implementation Method 3
An optical frequency conversion means of the single-photon source is adapted for converting the heralded photon corresponding to the detected heralding photon into a single output photon with deterministic source frequency f src
Data Source
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AI summary
A quasi-deterministic single-photon source (10) and method of generating single photons on demand are disclosed. The single-photon source comprises a photon pair generation means (11) for generating a heralding and heralded photon in a frequency-correlated photon pair, a single-photon spectrometer (12) adapted to detect the heralding photon and to generate an output signal that is indicative of the frequency (fi) of the detected heralding photon, a pulse shaper arrangement (13) for reshaping a broadband pulse, and an optical frequency conversion means (14) for converting, upon irradiation with a reshaped pulse, a heralded photon into a single output photon with deterministic source frequency (fsrc). The pulse shaper arrangement is configured to select, based on the spectrometer output signal, only frequency components (fsel) of the broadband pulse that is substantially coincide with the heralding photon frequency (fi) or with a constant detuning thereof.