Photon Number Resolving Detector Using Quantum Memory Multiplexing
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Solution Overview
Problem
Current photon number resolving detectors, such as time-multiplexing detectors, face challenges with increased photon attenuation and larger size due to the need for longer optical fiber lengths, which reduces their reliability and efficiency.
Innovation Solution
A photon number resolving detector system utilizing a plurality of optical couplers and dual path spans with quantum memories, where the quantum memories delay photon pulses, allowing for time-division multiplexing without the need for extended fiber lengths, thereby reducing attenuation and system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If increased lengths of fiber segments are used in time-multiplexing detectors, then the photon number resolving capability is improved, but photon attenuation increases and system size increases
Solution Approach 1:
The patent transitions from spatial dimension (long fiber segments) to temporal dimension (time-multiplexing with quantum memories) to achieve photon number resolution. By storing photons in quantum memories and releasing them at different times, the system resolves photon numbers without requiring long fiber lengths, thus avoiding photon attenuation while maintaining measurement precision.
Solution Approach 2:
Quantum memories are introduced as intermediary devices between the photon source and detectors. These quantum memories temporarily store photons and release them in a time-multiplexed manner, enabling photon number resolution without direct transmission through long attenuating fiber segments.
2Measurement precision
If increased lengths of fiber segments are used in time-multiplexing detectors, then the photon number resolving capability is improved, but the overall system size increases
Solution Approach 1:
The patent resolves photon numbers by exploiting the temporal dimension through quantum memory storage and time-multiplexed release, rather than using spatial extension via long fiber segments. This dimensional transformation enables compact system design while maintaining photon number resolving capability.
Solution Approach 2:
The system uses multiple copies of short fiber segments connected through quantum memories, rather than one long fiber segment. Each short segment is replicated and time-multiplexed, achieving the same photon number resolution function with reduced individual component lengths and overall system compactness.
3Measurement precision
If a large number of single photon detectors are used in space division detectors, then the photon number resolving capability is improved, but the device complexity increases
Solution Approach 1:
The patent makes two single-photon detectors universal by using quantum memories to direct different numbers of photons to these detectors in a time-multiplexed manner. The same two detectors can resolve any photon number by varying the time-multiplexing scheme, eliminating the need for multiple detectors required in space-division approaches.
Solution Approach 2:
The system transitions from spatial multiplexing (multiple detectors in parallel) to temporal multiplexing (fewer detectors used sequentially in time). By storing photons in quantum memories and releasing them at different times, the patent achieves photon number resolution with fewer detectors, reducing device complexity while maintaining measurement precision.
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
This approach enhances the efficiency and reduces the overall size of the detector system while enabling the use of photon detectors with higher detector dead times, improving the accuracy and reliability of photon counting.
Implementation Method 1
a delayed path having a quantum memory positioned between and optically coupled to an input sub-link and an output sub-link
Data Source
AI summary
A photon number resolving detector system includes a photon source positioned at an input end, first and second photon detectors positioned at a detection end, and a plurality of optical couplers positioned between the input and detection ends. The plurality of optical couplers include an initial optical coupler optically coupled to the photon source, a final optical coupler optically coupled to the first and second photon detectors, and intermediate optical couplers positioned between the initial optical coupler and the final optical coupler. A first input link is optically coupled to the photon source and the initial optical coupler and a plurality of dual path spans are optically coupled to adjacent optical couplers. The plurality of dual path spans each include an undelayed path having an undelayed fiber link and a delayed path having a quantum memory positioned between and optically coupled to input and output sub-links.