Probing Dark Matter-Electron Interactions with Superconducting Qubits

TL;DR

This work demonstrates that superconducting transmon qubits can place leading laboratory constraints on sub-GeV dark matter by tying DM energy deposition to quasiparticle generation in the qubit. The authors connect DM–electron scattering and dark photon absorption to measurable decoherence through the master equation $\dot{x}_{\rm qp} = \Gamma_G - r x_{ m qp}^2 - s x_{ m qp}$ and the loss-function formalism for the target material, yielding a bound $\Gamma_G \ge D_{\rm dm}/(2 \Delta^2 \nu_0)$ and a calculable $D_{\rm dm}$ via ${\rm Im}[ -1/\epsilon_L(\omega, {\bf q}) ]$. By re-analyzing state-of-the-art transmon data (including a residual quasiparticle fraction $x_{\rm qp} = 5.6 \times 10^{-10}$ at $T=20\,\mathrm{mK}$) with trapping and recombination dynamics, the study derives the strongest terrestrial constraints on DM–electron scattering for $m_{\chi}\sim 1$–$100\ \mathrm{keV}$ and competitive limits on dark photon absorption, with notable gains anticipated from improved QP control and thin-layer geometries. Overall, the results establish superconducting qubits as scalable, sensitive sensors for low-mass DM and outline concrete paths to stronger future limits.

Abstract

Quantum device measurements are powerful tools to probe dark matter interactions. Among these, transmon qubits stand out for their ability to suppress external noise while remaining highly sensitive to tiny energy deposits. Ambient galactic halo dark matter interacting with electrons can deposit energy in the qubit, leading to changes in its decoherence time. Recent measurements of transmons have consistently measured, in various experimental setups, a residual contribution to the decoherence time unexplained by thermal noise or known external sources. We use such measurements to set the most stringent laboratory-based constraints to date on dark matter-electron scattering at the keV scale and competitive constraints on dark photon absorption.

Figures (2)

• Figure 1: Al loss function.Top: The bulk Al-based transmon response. We describe the overall response of Al by a Lindhard function, augmented by a near-superconducting-gap correction factor. For $q$ smaller than a few hundred eV, the loss is approximately momentum-independent. Bottom: The transmon loss function including momenta-dependent corrections due to the thin layer geometry, with momenta deposits taken parallel to the layer. Both panels: The thick (thin) solid colored curves delineate the bulk (or thin-layer) response for representative values of the momenta magnitude $q$, and the gray line delineates the superconducting gap. For $q \gtrsim 2\, {\rm keV} \gg d^{-1}$, with $d$ the Al layer thickness, there is no discernible difference between the bulk and thin-layer loss functions.
• Figure 2: DM-electron interaction constraints from transmons.Left: Constraints on DM-electron scattering. We show limits on the reference cross section for galactic halo DM interacting with electrons via a light mediator, as derived from transmon measurements. The results obtained from the data of Ref. Connolly:2023gww for different values of $s$ are shown as solid blue lines, while the limit placed via the measurement of Ref. Riste:2013zqw is indicated by the pink dotted line. The blue hatched region depicts the enhanced reach from the thin layer geometry (see text for details). The projected sensitivity for a quantum device with $s = 10~{\rm Hz}$ and $x_{\rm qp} = 10^{-11}$ is shown as a solid orange line. The gray-shaded region represents existing experimental constraints QROCODILE:2024zmgSENSEI:2025qvpDAMIC-M:2025luv. Constraints may be relaxed for $\overline{\sigma}_e \gtrsim 10^{-23}\ {\rm cm}^2$ due to atmospheric scattering (see text). Right: Constraints on dark photon DM absorption. We display upper bounds on the kinetic mixing parameter of dark photon DM obtained from the data of Ref. Connolly:2023gww for different values of $s$, shown as solid blue lines of varying thickness. The limit extracted from the measurement of Ref. Riste:2013zqw is shown as an orange dotted line, and the projected sensitivity for a device with $x_{\rm qp} = 10^{-11}$ and $s = 10~{\rm Hz}$ is indicated by the dashed blue line. The gray-shaded region indicates existing terrestrial constraints assuming dark photon DM EDELWEISS:2019vjvEDELWEISS:2022kttDarkSide-50:2022qzhFranco:2023sjxSuperCDMS:2020ausSuperCDMS:2023sqlCRESST:2019jnqSENSEI:2023zdfPandaX:2023xglLUX:2018akbEssig:2019xkxQROCODILE:2024zmgBarak:2020fqlAmaral:2020rynAguilar-Arevalo:2019wdiEssig:2017kqsAgnes:2018oejXENON:2019gfnAn:2014twaAgnese:2018colAguilar-Arevalo:2019wdiArnaud:2020svbFUNKExperiment:2020ofvBarak:2020fql. The yellow-shaded region indicates complementary stellar constraints on dark photon absorption An:2013yuaAn:2020bxd, while the green-shaded area represents laboratory bounds on photon–dark photon conversion Bahre:2013ywa.