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Register a new userAxion search with a quantum-limited ferromagnetic haloscope
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A ferromagnetic axion haloscope searches for Dark Matter in the form of axions by exploiting their interaction with electronic spins. It is composed of an axion-to-electromagnetic field transducer coupled to a sensitive rf detector. The former is a photon-magnon hybrid system, and the latter is based on a quantum-limited Josephson parametric amplifier. The hybrid system consists of ten 2.1 mm diameter YIG spheres coupled to a single microwave cavity mode by means of a static magnetic field. Our setup is the most sensitive rf spin-magnetometer ever realized. The minimum detectable field is $5.5times10^{-19},$T with 9 h integration time, corresponding to a limit on the axion-electron coupling constant $g_{aee}le1.7times10^{-11}$ at 95% CL. The scientific run of our haloscope resulted in the best limit on DM-axions to electron coupling constant in a frequency span of about 120 MHz, corresponding to the axion mass range $42.4$-$43.1,mu$eV. This is also the first apparatus to perform an axion mass scanning by changing the static magnetic field.
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We present the first results of a search for invisible axion dark matter using a multiple-cell cavity haloscope. This cavity concept was proposed to provide a highly efficient approach to high mass regions compared to the conventional multiple-cavity design, with larger detection volume, simpler detector setup, and unique phase-matching mechanism. Searches with a double-cell cavity superseded previous reports for the axion-photon coupling over the mass range between 13.0 and 13.9$,mu$eV. This result not only demonstrates the novelty of the cavity concept for high-mass axion searches, but also suggests it can make considerable contributions to the next-generation experiments.
Axions, originally proposed to solve the strong CP problem of quantum chromodynamics, emerge now as leading candidates of WISP dark matter. The rich phenomenology associated to the light and stable QCD axion can be described as an effective magnetic field that can be experimentally investigated. For the QUAX experiment, dark matter axions are searched by means of their resonant interactions with electronic spins in a magnetized sample. In principle, axion-induced magnetization changes can be detected by embedding a sample in an rf cavity in a static magnetic field. In this work we describe the operation of a prototype ferromagnetic haloscope, with a sensitivity limited by thermal fluctuations and receiver noise. With a preliminary dark matter search, we are able to set an upper limit on the coupling constant of DFSZ axions to electrons $g_{aee}<4.9times10^{-10}$ at 95% C.L. for a mass of $58,mu$eV (i.,e. 14,GHz). This is the first experimental result with an apparatus exploiting the coupling between cosmological axions and electrons.
We generalize the recently proposed $mathcal{PT}$-symmetric axion haloscope to a larger array with more $mathcal{PT}$-symmetric structures. The optimized signal-to-noise ratio (SNR) has a greater enhancement, as well as the signal power. Furthermore, we show that the robustness of the detector towards the variations of the array coupling is the strongest when a binary tree structure is introduced which contains a largely enhanced $mathcal{PT}$ symmetry. The multiple allowed probing sensors can further increase the SNR by a factor of sensors number due to the correlation of the signals. This type of array can strongly boost the search for axion compared to single mode resonant detection. The enhancement to the SNR becomes the most manifest when applied to the newly proposed detection using superconducting radiofrequency caivty with AC magnetic field where most of the parameter space of the QCD axion above kHz can be probed.
The axion provides a solution for the strong CP problem and is one of the leading candidates for dark matter. This paper proposes an axion detection scheme based on quantum nondemolition detection of magnon, i.e., quanta of collective spin excitations in solid, which is expected to be excited by the axion-electron interaction predicted by the Dine-Fischer-Srednicki-Zhitnitsky (DFSZ) model. The prototype detector is composed of a ferromagnetic sphere as an electronic spin target and a superconducting qubit. Both of these are embedded inside a microwave cavity, which leads to a coherent effective interaction between the uniform magnetostatic mode in the ferromagnetic crystal and the qubit. An upper limit for the coupling constant between an axion and an electron is obtained as $g_{aee}<1.6times10^{-7}$ at the 95% confidence level for the axion mass of $33.117$$mu$eV$<m_{a}<33.130$$mu$eV.
The axion is an intriguing dark matter candidate emerging from the Peccei-Quinn solution to the strong CP problem. Current experimental searches for axion dark matter focus on the axion mass range below 40 $mu$eV. However, if the Peccei-Quinn symmetry is restored after inflation the observed dark matter density points to an axion mass around 100 $mu$eV. A new project based on axion-photon conversion at the transition between different dielectric media is presented. By using $sim 80$ dielectric discs, the emitted power could be enhanced by a factor of $sim 10^5$ over that from a single mirror (flat dish antenna). Within a 10 T magnetic field, this could be enough to detect $sim 100 mu$eV axions with HEMT linear amplifiers. The design for an experiment is proposed. Results from noise, transmissivity and reflectivity measurements obtained in a prototype setup are presented. The expected sensitivity is shown.
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