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The application of modern micro- and nanofabrication techniques to superconducting and cryogenic electronics is enabling new capabilities and applications.



FIB cross section of a SQUID multiplexer integrated circuit
Focused Ion Beam (FIB) cross section of a SQUID multiplexer integrated circuit fabricated in the Quantum Sensors Group.  This image shows the both the plan and cross sectional views of a small region of flux-addressed switch used in our time-division multiplexers.  The process uses Nb/AlOx/Nb junctions and has 3 Nb wiring layers.

The work of the Fabrication Project is the foundation of the Quantum Sensors Group. Members of the Fabrication Project use the Boulder Microfabrication Facility to make novel sensors and readout circuitry.  Standard circuits include Transition-Edge Sensors (TESs), Microwave Kinetic Inductance Detectors (MKIDs), Superconductor-Insulator-Superconductor (SIS) junctions, Normal-Insulator-Superconductor (NIS) junctions, Superconducting Quantum Interference Devices (SQUIDs), microwave feedhorns, and parametric amplifiers. The Fabrication Project frequently develops new processes and techniques in order to provide new capabilities to the Quantum Sensors Group and its collaborators. One present area of innovation is integrating multiple types of circuits on a common substrate.  Examples include combining NIS tunnel junction refrigerators with TES sensors and combining microwave SQUID multiplexers with TES sensors.

Major Accomplishments

  • Development and successful deployment of multichroic microwave polarimeters, including on 150 mm diameter substrates
  • Development of background-limited MKID sensors on 100 mm diameter substrates
  • Development of corrugated and spline-profile feedhorns from stacks of micromachined silicon platelets


detector and feedhorn arrays
Photographs of detector and feedhorn arrays for the Advanced ACT receiver fabricated in the Quantum Sensors group. The detector array (a) integrates superconducting microwave components, AlMn transition edge sensors and micro-machined features to create a large and sensitive multi-chroic camera for observation of the cosmic microwave background. The feedhorn array (b) forms part of the antenna structure for this detector and is fabricated by stacking many micro-machines silicon wafers to create an array or feedhorns.
Created November 19, 2008, Updated January 9, 2023