Broadening frequency range of a ferromagnetic axion haloscope with strongly coupled cavity–magnon polaritons

Abstract

With the axion being a prime candidate for dark matter, there has been some recent interest in direct detection through a so called 'Ferromagnetic haloscope.' Such devices exploit the coupling between axions and electrons in the form of collective spin excitations of magnetic materials with the readout through a microwave cavity. Here, we present a new, general, theoretical treatment of such experiments in a Hamiltonian formulation for strongly coupled magnons and photons, which hybridise as cavity-magnon polaritons. Such strongly coupled systems have an extended measurable dispersive regime. Thus, we extend the analysis and operation of such experiments into the dispersive regime, which allows any ferromagnetic haloscope to achieve improved bandwidth with respect to the axion mass parameter space. This experiment was implemented in a cryogenic setup, and initial search results are presented setting laboratory limits on the axion-electron coupling strength of g aee > 3.7 × 10 −9 in the range 33.79 µeV< m a < 33.94 µeV with 95% confidence. The potential bandwidth of the Ferromagnetic haloscope was calculated to be in two bands, the first of about 1 GHz around 8.24 GHz (or 4.1 µeV mass range around 34.1 µeV) and the second of about 1.6 GHz around 10 GHz (6.6 µeV mass range around 41.4 µeV). Frequency tuning may also be easily achieved via an external magnetic field which changes the ferromagnetic resonant frequency with respect to the cavity frequency. The requirements necessary for future improvements to reach the DFSZ axion model band are discussed in the paper.

Experimental implementations of cavity-magnon systems: from ultra strong coupling to applications in precision measurement

“…Applications of such systems range from quantum information processing [1][2][3] and coherent conversion of microwave to optical frequency light [4,5], to microwave components in the form of filters, circulators, isolators and oscillators. Additionally, such systems are used in the study of hybrid quantum systems [6,7], Quantum electrodynamics (QED) [8][9][10], and direct detection of dark matter [11][12][13][14][15]. In the context of dark matter detection, it has been shown that strongly coupled cavity-magnon systems are useful for expanding the range of detectable dark matter masses [11].…”

“…Additionally, such systems are used in the study of hybrid quantum systems [6,7], Quantum electrodynamics (QED) [8][9][10], and direct detection of dark matter [11][12][13][14][15]. In the context of dark matter detection, it has been shown that strongly coupled cavity-magnon systems are useful for expanding the range of detectable dark matter masses [11]. Typically, the material of choice for these experiments is Yttrium Iron Garnet (YIG) due to its low magnonic and photonic loss, and high spin density, however, other ferrimagnetic materials are often considered for study such as lithium ferrite (LiFe) [16] and Cu 2 OSeO 3 [17].…”

Detecting Light Dark Matter with Magnons

“…Finally, the gapless modes can also be lifted by an external magnetic field, which can be tuned to scan the DM mass, as considered in Refs. [52][53][54] (see also Ref. [65]) in the context of axion absorption.…”

Dissipation-Based Quantum Sensing of Magnons with a Superconducting Qubit

“…The demonstrated level of sensitivity represents a significant advancement relative to existing magnon detection schemes, where the typical quantity of detected magnons is many orders of magnitude larger [28,29,46]. Furthermore, detection on the level of single magnons and below can be useful for probing magneto-optical effects in the quantum regime as part of the development of quantum transducers [21,23], and may be used in dark matter searches for axionlike particles [47][48][49][50]. The device can also be used as a static magnetic field sensor, as the detuning of the Kittel mode by such a field is measurable by monitoring the magnon population excited by a fixed microwave drive.…”