A Flux-Tunable cavity for Dark matter detection

TL;DR

This paper introduces an electronically tunable superconducting cavity for dark matter detection, enabling wide frequency range searches with high sensitivity in cryogenic environments.

Contribution

The work presents a novel flux-tunable cavity architecture coupled with a quantum-limited detection method for dark matter searches, overcoming mechanical tuning challenges.

Findings

Constrained the kinetic mixing angle to < 8.2×10⁻¹⁵ in the 5.672-5.694 GHz band.

Achieved quantum-limited sensitivity in a cryogenic environment.

Demonstrated potential for wider frequency range searches with multimode cavities.

Abstract

Developing a dark matter detector with wide mass tunability is an immensely desirable property, yet it is challenging due to maintaining strong sensitivity. Resonant cavities for dark matter detection have traditionally employed mechanical tuning, moving parts around to change electromagnetic boundary conditions. However, these cavities have proven challenging to operate in sub-Kelvin cryogenic environments due to differential thermal contraction, low heat capacities, and low thermal conductivities. Instead, we develop an electronically tunable cavity architecture by coupling a superconducting 3D microwave cavity with a DC flux tunable SQUID. With a flux delivery system engineered to maintain high coherence in the cavity, we perform a hidden-photon dark matter search below the quantum-limited threshold. A microwave photon counting technique is employed through repeated quantum non-demolition measurements using a transmon qubit. With this device, we perform a hidden-photon search and constrain the kinetic mixing angle to ${\varepsilon}< 8.2\times 10^{-15}$ in a tunable band from 5.672 GHz to 5.694 GHz. By coupling multimode tunable cavities to the transmon, wider hidden-photon searching ranges are possible.