Akira Miyazaki (CNRS)

Towards search for 100 µeV axions and axion dark matter with high-frequency microwaves

Abstract: Axion is an attractive solution to the strong CP problem and potentially a bosonic dark matter candidate. Recently, other hypothetical light particles that interact with photons, such as scalar (dilaton) and vector (dark photons), are unified as axion-like particles (or simply axions) because they can be addressed with basically the same experimental techniques. Such axions have been searched via various photon frequencies. Amongst all previous experiments, the most successful search would be the cavity-based dark matter axion search, represented by the ADMX project. Despite the success of ADMX-like projects around a few µeV mass range, it has been technically a long-lasting problem to extend it towards a higher mass range (40-100 µeV). This parameter range is crucial in the so-called post-inflationary scenario of dark matter axions. In this seminar, we overview recent progress in this research domain. In most of the ongoing projects, wavy features of axions are revealed. Another important aspect of modern axion search is quantum technology, namely, single photon counting to overcome the standard quantum limit. The mass range (40 - 100 µeV) corresponds to the frequency where state-of-the-art wave detection schemes and single photon counting would compete. We briefly discuss the research opportunities at this point.