A 1,820 channel microwave SQUID multiplexer for TES bolometer readout

Increasingly large arrays TES bolometers continue to be planned for future mm-wave observatories, but their scalability is limited by the associated cryogenic multiplexing readout. Microwave SQUID multiplexing is a natural candidate for future systems, as it already boasts a ~10x channel handling advantage over other readout schemes due to its large available bandwidth. By further doubling this bandwidth, the demonstration we present increases the multiplexing factor from the prior best of 910 to 1,820 and enables a simple 1:1 pairing of detector components and multiplexer hardware. We show a yield of greater than 80% based on TES IV curve quality and model typical nearest-neighbor crosstalk to be ~0.4%. Finally, we estimate from measurements that only 3% of the total noise budget would result from the multiplexer if installed in a typical sorption-cooled ground-based receiver observing 60 degrees above the horizon with a zenith precipitable water vapor of 1.3 mm.