Speaker
Description
Dark matter candidates on the mass scale of $\mathcal{O}(10-10^4)\,\mathrm{keV}$ produce $\mathcal{O}(1-10^3)\,\mathrm{meV}$ phonon excitations. Probing these low-mass dark matter candidates requires quantum sensors with meV phonon energy resolution ($\sigma_E$). Transition edge sensors (TESs) have achieved the lowest energy threshold so far, with $\sigma_E \sim \mathcal{O}(100)\,\mathrm{meV}$. On the other hand, the kinetic inductance phonon-mediated (KIPM) detectors have demonstrated 2.1 eV absorbed energy resolution ($\sigma_{E_{abs}}$) with a $\mathcal{O}(1)\%$ phonon collection efficiency. This contribution presents a pathway toward building a $\sigma_E \sim \mathcal{O}(1)\,\mathrm{meV}$ phonon-absorber-assisted (PAA) KIPM detector. Specifically, the meV KIPM energy resolution can be achieved by (1) reducing the intrinsic detector noises including the two-level-system (TLS) noise, amplifier noise, and the generation-recombination (GR) noise and (2) improving total efficiency, including the phonon collection efficiency ($\eta_{ph}$) and quasiparticle trapping efficiency ($\eta_{trap}$), to $\mathcal{O}(30)\%$ limited by the phonon pair breaking efficiency ($\eta_{pb}$), as demonstrated in quasiparticle-trap-assisted electrothermal-feedback
transition-edge sensors (QETs). Achieving both low noise and high efficiency requires implementing quasiparticle trapping, using aluminum (Al) absorbers and low $T_c$ inductors, to enable high active Al surface coverage and small inductor volume. Detailed noise studies and efficiency characterization are conducted to predict detector performance. This contribution briefly summarizes the latest PAA-KIPM design, expected detector performance, and fabrication and testing status.
