Progress toward a multiplexed readout of transition-edge sensors for CUPID-1T*

CUORE is an ongoing neutrinoless double-beta decay search using the isotope ¹³⁰Te. The next generation detector, CUORE with Upgraded Particle IDentification (CUPID), will use scintillation light from Li₂¹⁰⁰MoO₄ cryogenic calorimeters to tag particles by their heat-to-light signal ratio. CUPID is under development at the 250 kg level, but is looking to the next stage with 1 tonne of ¹⁰⁰Mo (CUPID-1T). Scaling the next generation of crystalline detectors to this size requires ten thousand channels or more. Efforts to decrease wire density using frequency-division multiplexing are ongoing, and require technical solutions to demonstrate performance at operating temperature; systems must also adhere to stringent noise, crosstalk, and radiopurity constraints. We discuss a collaboration between UC Berkeley and Lawrence Berkeley National Laboratory toward these technical solutions. Multiplexing systems developed at LBNL and currently in use for cosmic microwave background experiments were adapted and implemented in a dilution refrigerator at UCB. Applications to research beyond NDBD (dark matter, coherent neutrino scattering, and next-generation quantum computing) are also considered.