SeeQC (HYPRES) proposes to develop cryogenic multiplexing readout circuitry for superconducting sensor arrays. Our design and advanced multi-layer Niobium fabrication process will enable us to make a compact SQUID based readout for large scale superconducting bolometer arrays.
Arrays of superconducting transition edge sensors (TES) are frequently deployed in instruments for far infrared (IR) astronomy, particularly for cosmic microwave background (CMB) measurements. In order to reduce thermal loading due to wiring between the detectors and readout, as well as to reduce the cost of readout electronics, multiplexing has become a key technology for enabling detectors arrays at the kilo-pixel level and beyond. Multiplexing allows readout of multiple detectors on a single line by separating the signal from each detector in either the time or frequency domain. Current NASA missions employing time domain multiplexing (TDM) include HAWC+ and PIPER. These experiments feature a SQUID based TDM readout circuit that is interfaced to the TES array through an Indium bump bonding process.
Next generation missions such as PIPER Dual Polarization Upgrade and PICO require an increase in sensor desnsity. As part of subtopic S1.04 (Sensor and Detector Technologies for Visible, IR, Far-IR, and Submillimeter), NASA has put out a call for kilo-pixel scale cryogenic, multiplexed readout capable of reading out two TES per 1 mm2 pixel. SeeQC (HYPRES) will design and simulate a SQUID based TDM circuit with low noise and crosstalk that meets the above area requirements. We will also fabricate and test a small version to validate our design and demonstrate feasibility of the full scale array.
Transition edge sensors are used in both x-ray and far IR astronomy, including polarization sensitive cosmic microwave background measurements. Large format TES arrays, such as used by current NASA missions PIPER and HAWC+ require two-dimensional, cryogenic multiplexed readout. The multiplexer developed in this work will be compatible with these missions, as well as enabling future NASA missions such as PICO and the dual polarization upgrade to PIPER.
Because they reduce the heat load between the cold stage and higher temperatures, cryogenic multiplexers are an enabling technology for any superconducting sensor array. TES bolometer arrays are used in a variety of far IR astronomy experiments. TES calorimeter arrays are used for high resolution, time-resolved x-ray spectroscopy for applications such as nuclear physics and materials analysis.