Frequency Multiplexed TES Based Light Detectors for CUPID and Beyond

The search for neutrinoless double beta (0νββ) decay is ongoing and aims to determine whether the neutrino is Majorana in nature. Discovery of such a process would immediately imply lepton number violation and represent new physics beyond the standard model. This search has been ongoing for a few decades with multiple experimental strategies and choices of isotope. CUPID (CUORE Upgrade with Particle ID) is a next generation experiment searching for 0νββ decay in ¹⁰⁰Mo using enriched scintillating lithium molybdate (LMO) crystals and profiting from several years of experience gained with its predecessor, CUORE (Cryogenic Underground Observatory for Rare Events). CUPID will consist of 1596 LMO crystals operated as bolometers, coupled to 1710 light detectors allowing for the simultaneous readout of both heat and light energy. This allows for a reduction of alpha induced backgrounds due to differences in the amount of scintillation light produced by alpha events. 2νββ decay in ¹⁰⁰Mo has a sufficient rate to induce a non-negligible background from pile-up that requires fast light detectors to reject. A future ton-scale version of a CUPID like experiment would require faster sensors to avoid this background. Transition edge sensors (TES) are a promising technology offering both fast sensor response and excellent energy resolution. In order to avoid requiring a large number of SQUIDs to amplify the TES signals a solution developed by cosmic microwave background telescope experiments is digital frequency multiplexing. In this presentation we will provide an overview of work done on modifying this technology for use in a 0νββ decay experiment and present the current status and results of operating these frequency multiplexed TES devices.