Novel Light Dark Matter Detection with Quantum Parity Detector Using Qubit Arrays

TL;DR

The work proposes a cryogenic qubit-array detector with a novel two-chip, phonon-mediated dark matter sensor that uses a quantum parity detector to read out single-quasiparticle tunneling events. By simulating phonon transport, quasiparticle dynamics, and parity-based readout, the authors show near-unity detection efficiency for sub-eV energy depositions and a high energy resolution, enabling strong projected limits on DM–electron scattering and DM absorption (axions/dark photons) that surpass current constraints by orders of magnitude for sub-MeV DM. The approach leverages a sapphire target, AMM-based interface transmissions, and a 96-qubit array to achieve robust background discrimination, setting the stage for kilo-gram–year exposures and broad exploration of freeze-in/freeze-out DM scenarios. If realized, this technique could dramatically extend the accessible DM parameter space in the meV–eV regime, including dark photon and axion couplings, with tunable geometry and materials optimizing phonon–QP pathways. Overall, the paper demonstrates a credible path to a highly sensitive, scalable, and background-tolerant light DM detector based on quantum-parity readout of phonon-induced quasiparticles.

Abstract

We present the design and the sensitivity reach of the Qubit-based Light Dark Matter detection experiment. We propose the novel two-chip design to reduce signal dissipation, with quantum parity measurement to enhance single-phonon detection sensitivity. We demonstrate the performance of the detector with full phonon and quasiparticle simulations. The experiment is projected to detect $\gtrsim 30$ meV energy deposition with nearly $100\%$ efficiency and high energy resolution. The sensitivity to $m_χ\gtrsim 0.01$ MeV dark matter scattering cross section is expected to be advanced by orders of magnitude for both light and heavy mediators, and similar improvements will be achieved for axion and dark photon absorption in the $0.04$-$0.2$ eV mass range.

Figures (10)

• Figure 1: The schematic drawing of the qubit array and its details. (a) 96 qubits are distributed evenly on the upper slice of the chip, and the lower slice loads the readout, gate and control lines. The 3D structure of a single qubit is enlarged in (b). (c) The qubit response to DM interaction from the lateral view. The materials are labeled with different colors. (d) Lateral view of the full detector. (e) The energy split of the two lowest qubit levels due to even and odd charge parities. (f) The energy fraction of DM-induced phonons absorbed by the qubits as a function of the $x-y$ location of the interaction in the substrate from simulations.
• Figure 2: The blue lines show the detection efficiency as a function of the energy deposition from DM interaction for a thin-chip (dash-dotted) and a thick-chip (solid) detector. The dotted line marks the 10% efficiency. The colors depict the probability distribution of tunneling counts in all qubits in one measurement time window $N_{\rm obs}$ for a thin chip as a function of the energy deposition, and the white line marks the reconstructed energy corresponding to the maximum likelihood as a function of $N_{\rm obs}$.
• Figure 3: Upper: 90% C.L. sensitivity on DM-electron scattering cross section. Black lines correspond to different exposures using the detector design in this work. We also show existing constraints from the direct detection of halo DM SENSEI:2023zdfDAMIC-M:2023gxoDarkSide:2022knjXENON:2019gfnEDELWEISS:2020fxcPandaX-II:2021nsgSuperCDMS:2024yiv, and the DM accelerated and reflected by electrons in the Sun An:2021qdlEmken:2024nox. The green lines show the cross section to produce the correct DM relic density in the benchmark freeze-in process Essig:2011njChu:2011beEssig:2015cdaDvorkin:2019zdi for a light mediator (left) and freeze-out process Essig:2015cdaBoehm:2003hmLin:2011gjHochberg:2014draDAgnolo:2019zkfKahn:2021ttr for a heavy mediator (right). Lower: 90% C.L. sensitivity on DM absorption. For axion we also show existing constraints on axion-photon coupling $g_{a\gamma\gamma}$ from CAST CAST:2017uphCAST:2024eil, the globular clusters Ayala:2014peaDolan:2022kul and JWST Pinetti:2025owq (left). The blue band shows parameter space for QCD axion Peccei:1977urPeccei:1977hhWilczek:1977pjWeinberg:1975uiAxionLimits. For dark photon we show limits on kinetic mixing $\kappa$ from solar cooling Vinyoles:2015abaAn:2013yfcLi:2023vpv (right).
• Figure S1: The phonon spectra of sapphire computed using DFT with the VASP code. The letters in the $x$-axis label the high symmetry points in the Brillouin zone. Different colors mark the paths between different points.
• Figure S2: (a) Schematic illustration of the qubit circuit. The qubit (green) comprises a Superconducting Quantum Interference Device (SQUID) and a large shunted capacitance $C_B$, where $\Phi$ is the node flux. The SQUID can be tuned by the external flux $\Phi_\text{ext}$. This qubit can be controlled by a gate voltage $V_g$ (yellow) through capacitance $C_g$ and current drive $I_d$ (blue) through mutual inductance, respectively. To realize a qubit readout, we capacitively couple a LC resonator to the qubit and followed by a readout transmission chain (brown). (b) The charge-parity detection process. The qubit state and charge-parity state at each step of the circuit are depicted on a Bloch sphere. (c) The behavior of a qubit array when capturing a signal.