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English: Microdevices Laboratory (MDL) has been involved at the forefront of superconducting materials research for many decades. It continues still, with an immense range of applications to NASA science and technology.

The small energy gap and strong non-linearity of superconducting materials render them uniquely suited for ultra-sensitive detectors and electronics. MDL develops and deploys novel superconducting and related non-superconducting sensor technologies for application in areas such as astrophysics, optical communications, quantum computing, Earth, planetary, and cometary sciences.

Beginning in the early 1980s, cryogenic sensor research at JPL focused on superconductor-insulator-superconductor (SIS) heterodyne mixers for astrophysical applications. In collaboration with Caltech, MDL SIS millimeter- and submillimeter-wave mixer technology was deployed in terrestrial radio telescopes, balloon and airborne observatories, and the Herschel Space Observatory. Current development is aimed at cometary water observations. MDL was also an early leader in developing and deploying Hot Electron Bolometer (HEB) mixers, primarily for frequencies above 1 THz. MDL is also developing Josephson and HEB mixers based on the high-temperature superconductor MgB2 for frequencies above 1 THz and/or for operation at temperatures up to 20 K.

In parallel with these mixer developments, there has been long-term involvement with direct detectors, such as transition-edge sensors (TES). Increasingly complex focal plane arrays based on superconducting TES have been, and are being, deployed at the South Pole on several generations of radio telescopes to gather cosmic microwave background polarization measurements at millimeter wavelengths. A more recent innovation, and a potential replacement for TES devices are Thermal Kinetic Inductance Detectors (TKIDs). TKIDs are bolometers that use the thermally sensitive kinetic inductance of a superconducting film in a resonator to monitor temperature shifts from changes in loading. These detectors offer multiplexing that is extendible to large arrays.

JPL engineers are developing a flexible microwave readout system applicable to all types of kinetic inductance detectors and related sensors. It uses commercial off-the-shelf software-defined radios that generate radio frequency interrogation tones and digitized response from cryogenic cameras. The software radio streams this data by high-speed Ethernet to a desktop computer that demodulates and filters the data, accelerating demanding computations in the computer’s graphics card. This system is more flexible than a field-programmable gate array-based solution because it is programmed with conventional languages and is already facilitating the study of novel readout techniques.