  The future Ricochet experiment aims to search for new physics in the
electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus
Scattering process from reactor antineutrinos with high precision down to the
sub-100 eV nuclear recoil energy range. While the Ricochet collaboration is
currently building the experimental setup at the reactor site, it is also
finalizing the cryogenic detector arrays that will be integrated into the
cryostat at the Institut Laue Langevin in early 2024. In this paper, we report
on recent progress from the Ge cryogenic detector technology, called the
CryoCube. More specifically, we present the first demonstration of a 30~eVee
(electron equivalent) baseline ionization resolution (RMS) achieved with an
early design of the detector assembly and its dedicated High Electron Mobility
Transistor (HEMT) based front-end electronics. This represents an order of
magnitude improvement over the best ionization resolutions obtained on similar
heat-and-ionization germanium cryogenic detectors from the EDELWEISS and
SuperCDMS dark matter experiments, and a factor of three improvement compared
to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II
germanium detector. Additionally, we discuss the implications of these results
in the context of the future Ricochet experiment and its expected background
mitigation performance.
