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The Cosmic Microwave Background (CMB) has provided an invaluable source of information about the universe we live in. However, much information is yet to be gained. For instance, information about the cosmological parameters of dark energy, inflation, and the neutrino sector is nearly guaranteed to provide revolutionary results in upcoming CMB experiments.
The current most popular detector technology, TES bolometers, finds a challenge in its low-noise readout, which requires a per-detector strong voltage bias while being able to sense O(10 aW/rtHz) fluctations in incident power. Frequency-multiplexed (fMUX) readout has been demonstrated to great success with an O(10) multiplexing factor, and is currently being implemented with an O(100) multiplexing factor for SPT-3G and POLARBEAR-2. We are developing a series of improvements that will greatly simplify the fMUX readout architecture, improve performance, and increase the multiplexing factor.
I will present results on a lossless method of fMUX detector bias that simplifies the readout architecture, as well as an effort to radically change and further simplify the readout architecture by moving the 4K DC SQUID to the sub-Kelvin stage.
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