Speaker
Description
A basic design principle of axion dark matter microwave cavity experiments, such as ORGAN, HAYSTACK, and ADMX, is the haloscopic scaling with the square root of the cavity for the sized of the oscillating electric field at the axion Compton frequency created by axion-to-photon conversion in the static magnetic field within the cavity. Yet, wave-like dark matter magneto-optical experiments, such as WISPFI, ALPS-II, and PVLAS, often go to great lengths to cut the laser beam waist within the transverse magnetic field where photon-to-axion conversion is to take place. Adapting the haloscopic scaling to the magneto-optical experiment context, we propose to determine the axion Compton frequency to 8 parts per billion (ppb) precision in a couple hours of integration time using a dark-fringe phase-locked free-space Mach-Zehnder interferometer with a modest dipole magnetic field from a custom-built permanent-magnet assembly in the sensing arm (1 T, 40 cm long, 6 mm pole gap), driven by a relatively cheap tunable near-infrared laser (3 mW, 1 MHz linewidth, 2458 nm wavelength), and read out at the dark-port by an off-the-shelf photodiode detector (200 fW/sqrt(Hz) noise-equivalent power, 1 mm aperture). Besides the broad beam waist, the key to the proposal is the frequency-modulation of the laser through a relatively narrow band, about 100 MHz wide, around a novel first-principles high-precision prediction for the axion Compton frequency, around 122 THz, that comes from a simple yet compelling physical picture for the nature of dark matter, dark energy, and the Big Bang.
| Primary Abstract Topic | Experiment: Axions and Wave-Like-DM |
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