Photon Number Resolving Superconducting Detector Segmentation
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Solution Overview
Problem
Current superconducting photon detectors are not ideal for resolving the number of incident photons due to their sensitivity to single photons, which causes the entire detector to transition to a non-superconducting state, making it difficult to discriminate between single and multiple photon absorptions.
Innovation Solution
A photon detector with a superconducting wire having alternating narrow and wide portions, optically coupled to an optical waveguide, and electrically coupled to a current source, allowing the wire to maintain a superconducting state in the absence of photons. The narrow portions are designed to transition to a non-superconducting state upon photon absorption, while the wide portions act as buffer regions, enabling the detection of multiple photons without transitioning the entire wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the superconducting wire is made highly sensitive to detect single photons, then the detection capability for single photons is improved, but the entire wire transitions to non-superconducting state making it difficult to discriminate between single and multiple photon absorptions
Solution Approach 1:
The superconducting wire is divided into multiple segments with different critical current densities. The first plurality of segments have a first critical current density optimized for single photon detection, while the second plurality of segments have a second critical current density that is higher and distinct from the first. This segmentation allows independent response characteristics for different photon numbers, enabling both single photon detection and photon number discrimination.
Solution Approach 2:
Different portions of the superconducting wire are given different local properties through varying critical current densities in different segments. The first segments are designed with lower critical current density for high sensitivity to single photons, while the second segments have higher critical current density to remain superconducting under normal operation but transition at higher photon numbers. This local differentiation enables simultaneous optimization for both detection sensitivity and photon number resolution.
2Stability of the object's composition
If the superconducting wire is designed to maintain superconducting state in absence of photons, then the baseline stability is improved, but the wire cannot resolve multiple photon absorptions due to complete state transition
Solution Approach 1:
The wire is segmented into multiple regions with different critical current densities, creating a distributed response system. When photons are absorbed, different segments transition at different thresholds, allowing the system to maintain partial superconducting state and resolve multiple photon numbers without complete state transition.
Solution Approach 2:
The critical current density parameter is varied across different segments of the wire. By controlling this parameter distribution, the wire can maintain superconducting state under normal conditions (high stability) while transitioning selectively in specific segments when multiple photons are absorbed, enabling photon number resolution without losing baseline stability.
3Ease of manufacture
If the superconducting wire uses uniform critical current density, then the manufacturing simplicity is improved, but the ability to discriminate between single and multiple photon absorptions is lost
Solution Approach 1:
The wire is divided into multiple segments during fabrication, with each segment having a distinct critical current density. This segmentation can be achieved through standard fabrication techniques by creating regions with different superconducting material properties or geometric characteristics, maintaining manufacturability while enabling photon number discrimination through the segmented response characteristics.
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 design allows for the discrimination between single and multiple photon absorptions by measuring the electrical resistance changes, effectively resolving the number of incident photons and improving the device's yield and reliability.
Implementation Method 1
a superconducting wire having a plurality of alternating narrow and wide portions... configured to maintain the superconducting wire in a superconducting state in the absence of incident photons
Implementation Method 2
The narrow portions are designed to transition to a non-superconducting state upon photon absorption
Data Source
AI summary
A method of resolving a number of photons received by a photon detector includes optically coupling a waveguide to a superconducting wire having alternating narrow and wide portions; electrically coupling the superconducting wire to a current source; and electrically coupling an electrical contact in parallel with the superconducting wire. The electrical contact has a resistance less than a resistance of the superconducting wire while at least one narrow portion of the superconducting wire is in a non-superconducting state. The method includes providing to the superconducting wire, from the current source, a current configured to maintain the superconducting wire in a superconducting state in the absence of incident photons; receiving one or more photons via the waveguide; measuring an electrical property of the superconducting wire, proportional to a number of photons incident on the superconducting wire; and determining the number of received photons based on the electrical property.