Dark graviton sensing with magnetically levitated superconductors

TL;DR

This paper explores how magnetically levitated superconductors can detect dark gravitons, focusing on their responses to matter and light couplings, and assesses their potential sensitivity compared to existing experiments.

Contribution

It introduces a novel approach to detect dark gravitons using levitated superconductors and analyzes their response to different couplings in the low-frequency range.

Findings

Matter coupling produces a tidal acceleration similar to a gravitational wave.

Light coupling induces an oscillating magnetic field in the superconductor.

Sensitivity to matter coupling is less competitive than existing experiments, but electromagnetism coupling shows promise.

Abstract

Levitated sensors have emerged as a new frontier to detect ultra-light dark matter such as axion-like particles and dark photons. In this work we study how a magnetically levitated superconductor responds to a spin-2 dark matter field, the dark graviton, in the dHz to kHz frequency range. To do so, we compute the forces that the dark graviton exerts on the superconductor, separately for matter and light couplings. The matter coupling produces a strain-like tidal acceleration between the superconductor and the readout pick-up loop in a way that is akin to a slow, continuous, massive gravitational wave. The light coupling instead induces an effective current that sources an oscillating magnetic field, thus driving the superdiamagnetic response of the superconductor. We find that, even with significant experimental improvements, the sensitivity reach for the matter coupling is not competitive with existing interferometers or fifth-force experiments. On the other hand, magnetically levitated superconductors could be among the most sensitive laboratory probes of the dark-graviton coupling to electromagnetism, especially at low frequencies, provided technical and readout noise can be kept under control.