Speaker
Description
Axions were originally proposed to solve the strong CP problem and are among the leading candidates for ultralight dark matter in cosmology. In contrast to particle-like dark matter candidates such as Weakly Interacting Massive Particles (WIMPs) and Freeze-In Massive Particles (FIMPs), axions and axion-like particles can be described as a classical field. This behavior arises from their large occupation number and macroscopic de Broglie wavelength, which lead to coherent, wave-like dynamics on laboratory scales.
In the presence of a static magnetic field, non-relativistic dark matter axions can be converted into microwave photons via the inverse Primakoff effect. The resulting signal is semi-classical and forms the basis of resonant and broadband detection strategies. Particular emphasis in this lecture course will be placed on the wake-like behavior of axion dark matter and its phenomenological differences from conventional particle-like dark matter candidates.
The course covers the theoretical foundations and experimental techniques of axion detection, progressing from basic principles to current state-of-the-art approaches and future directions. The structure is as follows:
5-1) Overview of axion searches
General introduction, theoretical framework, and a survey of ongoing and planned experiments worldwide.
5-2) Classical detection schemes
Microwave cavities and materials, resonator design, signal readout, and analog and digital signal processing.
5-3) Quantum detection schemes
Coherent states and Roy J. Glauber’s theorem, quantum noise and the standard quantum limit, squeezing techniques, and photon counting.
Because some of the required quantum optical concepts may be less familiar to particle physicists, Part 5-3 includes hands-on exercises on basic quantum optics. Participants are encouraged to bring pen and paper to work through operator manipulations in bra–ket notation.
