Superconducting Wire Thermometry for Low-Temperature Circuit Control
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Solution Overview
Problem
Existing electronic and optical circuit components, particularly those performing quantum operations, face temperature-dependent efficiency issues due to the temperature-dependent detection efficiencies of photon detectors, necessitating systems and methods for accurate temperature measurement and load balancing.
Innovation Solution
The use of superconducting wires thermally-coupled to heat-producing circuit components to measure temperature by determining the threshold superconducting current, which is more strongly dependent on thermal properties, allowing for precise temperature measurement and load balancing by transitioning between superconducting and non-superconducting states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature monitoring techniques are used, then temperature measurement is possible, but measurement precision deteriorates at low temperatures
Solution Approach 1:
The patent changes the measurement parameter from conventional resistance-based thermometry to superconducting transition-based detection. By utilizing the sharp transition in electrical resistance at the critical temperature of superconducting materials, the system achieves high-precision temperature measurement at low temperatures where conventional techniques fail. The superconducting wire's resistance drops abruptly from finite to zero at its critical temperature, providing a clear binary signal for precise temperature determination.
Solution Approach 2:
The patent employs composite material structures combining superconducting materials with dielectric materials. The superconducting wire is positioned in thermal contact with the device under test through a dielectric medium, creating a composite thermal pathway that enables accurate temperature sensing while maintaining electrical isolation. This composite approach allows the superconducting sensor to effectively probe the thermal state of the device at cryogenic temperatures.
2Measurement precision
If superconducting wires are placed close to the device for thermal coupling, then thermal sensitivity improves, but phonon interference from the device affects measurement accuracy
Solution Approach 1:
The patent introduces a dielectric material as an intermediary between the superconducting wire and the device under test. This dielectric medium serves as a thermal conductor that couples the wire to the device while simultaneously acting as a phonon filter. The dielectric material allows heat transfer for temperature sensing but blocks high-energy phonons that would otherwise directly interact with the superconducting wire and cause measurement errors or spurious transitions.
Solution Approach 2:
The patent creates different local thermal environments: the superconducting wire is positioned at a specific distance from the device surface, greater than the phonon mean free path in the dielectric. This spatial arrangement ensures that the wire senses the bulk thermal properties of the device rather than being directly affected by surface phonon emissions. The local quality of thermal coupling is optimized to achieve sensitivity while avoiding phonon interference.
3Measurement precision
If threshold superconducting current is used for temperature measurement, then temperature-dependent efficiency measurement is achieved, but device complexity increases
Solution Approach 1:
The patent employs self-service measurement techniques where the superconducting wire's own electrical properties are used to sense temperature. By monitoring the critical current at which the wire transitions from superconducting to normal state, the system achieves temperature measurement without requiring external sensors or complex measurement apparatus. The wire itself serves as both the thermal coupling element and the temperature sensor, simplifying the overall device architecture.
Solution Approach 2:
The superconducting wire performs multiple functions: it provides thermal coupling to the device, acts as a temperature sensor through its critical current characteristic, and can serve as part of the measurement circuitry. This multi-functionality reduces the need for separate dedicated temperature sensing components, thereby reducing overall 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
Enables effective temperature measurement, especially at low temperatures, and improves the efficiency and effectiveness of electronic and optical circuits by adjusting operations based on temperature, overcoming limitations of other temperature monitoring techniques.
Implementation Method 1
measuring a temperature of the first component based on whether the superconducting wire transitioned between the superconducting state to a non-superconducting state
Implementation Method 2
a superconducting wire is spaced more than a mean free path of phonons from the device, so as to better probe the bulk thermal properties of the device
Data Source
AI summary
An example method described herein includes operating a first component of a circuit. The method also includes, while operating the first component, supplying a current to a superconducting wire that is thermally-coupled to the first component, and determining whether the superconducting wire has transitioned between a superconducting state to a non-superconducting state in response to the current. The method further includes measuring a temperature of the first component based on whether the superconducting wire transitioned between the superconducting state to the non-superconducting state in response to the current, and adjusting operation of the first component in accordance with a determination that the temperature exceeds a predetermined threshold temperature.