Ben McAllister

Jun 3, 2024 | link.aps.org | Ben McAllister |John Street |Zijun C Zhao |Jeremy Bourhill

Silicon is a key semiconducting material for electrical devices and hybrid quantum systems where low temperatures and zero-spin isotopic purity can enhance quantum coherence. Electrical conductivity in Si is characterized by carrier freeze out at around 40 K allowing microwave transmission, which is a key component for addressing spins efficiently in silicon quantum technologies.

Jan 16, 2024 | link.aps.org | Aaron Quiskamp |Ben McAllister |John Street |Paul Altin

We report the results of Phase 1b of the ORGAN experiment, a microwave cavity haloscope searching for dark matter axions in the 107.42–111.93  μeV mass range. The search excludes axions with two-photon coupling gaγγ≥4×10−12  GeV−1 with 95% confidence interval, setting the best upper bound to date and with the required sensitivity to exclude the axionlike particle cogenesis model for dark matter in this range.

Jan 16, 2024 | link.aps.org | Ben McAllister |John R St |Aaron Quiskamp |QDM Lab

Axions are a compelling dark matter candidate, and one of the primary techniques employed to search for them is the axion haloscope, in which a resonant cavity is deployed inside a strong magnetic field so that some of the surrounding axions may convert into photons via the inverse Primakoff effect and become trapped inside the resonator. Resonant cavity design is critical to the sensitivity of a haloscope, and several geometries have been utilized and proposed.

Jun 6, 2023 | onlinelibrary.wiley.com | Ben McAllister |Paul Altin |Supercomputing Swinburne |Aaron Quiskamp

The typical axion–photon coupling is governed by the Lagrangian term L ⊃ − 1 4 g a γ γ a ( t ) F μ ν F ∼ μ ν $$\begin{equation} \mathcal {L} \supset -\frac{1}{4}g_{a\gamma \gamma }\, a(t) \, F^{\mu \nu } \widetilde{F}_{ \mu \nu }\, \end{equation}$$ (2)where F μ ν $F^{\mu \nu }$ and F ∼ μ ν $\widetilde{F}^{\mu \nu }$ are the electromagnetic field strength and its dual, and a ( t ) $a(t)$ is the oscillating axion field.

Jun 5, 2023 | link.aps.org | Catriona Thomson |Ben McAllister |John R St |Maxim Goryachev

Abstract We present new results of a room temperature resonant AC haloscope, which searches for axions via photon upconversion. Traditional haloscopes require a strong applied DC magnetic background field surrounding the haloscope cavity resonator, the resonant frequency of which is limited by available bore dimensions.