We present \textbf{GeQuLEP} (Germanium-based Quantum Sensors for Low-Energy Physics), a conceptual design for an advanced quantum sensing platform integrating high-purity germanium (Ge) crystals with engineered phononic crystal cavities. At cryogenic temperatures, these cavities naturally host dipole-bound states, effectively forming quantum dots coupled to radio-frequency quantum point contact (RF-QPC) readout systems. This innovative coupling approach promises ultra-sensitive phonon-mediated charge detection through phonon-induced charge displacement. GeQuLEP is specifically designed to achieve exceptionally low detection thresholds, theoretically enabling single primary phonon sensitivity with anticipated energy depositions as low as \textbf{0.00745~eV}. This unprecedented sensitivity, if realized experimentally, would provide unique access to searches for low-mass dark matter down to the keV/c2 mass range via nuclear and electronic recoils. Additionally, GeQuLEP aims to facilitate the real-time detection of solar \textit{pp} neutrinos through coherent elastic neutrino--nucleus scattering (CEνNS). By combining phonon-based quantum transduction with quantum-classical hybrid readout schemes, the GeQuLEP architecture represents a scalable, contact-free phonon spectroscopy design that could significantly advance the capabilities of ultra-low-energy rare-event detection at the quantum limit.
Cite
@article{arxiv.2507.01815,
title = {Ge-based Quantum Sensors for Low-Energy Physics},
author = {D. -M. Mei and N. Budhathoki and S. A. Panamaldeniya and K. -M. Dong and S. Bhattarai and A. Warren and A. Prem and S. Chhetri},
journal= {arXiv preprint arXiv:2507.01815},
year = {2025}
}