Axion Group
Experiments
The axion is a compelling dark matter candidate, also explaining why the neutron electric dipole moment is vanishingly small. Despite this attractive solution, the axion is still widely unconstrained, depending on different cosmological scenarios slightly favoring ∼µeV - meV masses. Its discovery would have far-reaching consequences for particle physics and astronomy.
Our group builds novel experiments to directly detect axion dark matter in this mass range. Axions can convert to photons under a strong magnetic field. We use this property to build electromagnetic resonators in strong magnets where axions can convert to photons. We combine these setups with the most sensitive photon detection schemes in existence. Our group contributes to the following experimental collaborations.
BREAD
BREAD is a concept to search for axions without resonant enhancement, but instead over a broad mass range instantaneously. This is particularly interesting for higher axion masses around the meV range (THz frequencies). BREAD uses a novel reflector geometry, shown on the left. This makes the non-resonant conversion concept (also called "dish antenna") compatible with readily available high-field solenoid magnets. BREAD has recently demonstrated a pilot experiment in the 12GHz regime (~50µeV), called GigaBREAD, and a demonstrator in the infrared regime, InfraBREAD, is underway. Our group will combine the BREAD concept with novel signal enhancement techniques and quantum sensors to achieve sensitivity in the GHz-THz regimes. We will perform these axion searches on the Harvard campus in a dedicated cryogenic high-field magnet.
ADMX
ADMX searches for the resonant conversion of µeV axions to GHz (radio frequency) photons using m-scale resonant cavities with quality factors above 104. Assuming axions make up all dark matter, ADMX has excluded the largest range of masses using this technique for the QCD axion at the DFSZ benchmark sensitivity, and is the world-leading experiment in the field. Our group will work on the design and testing of cavities for future higher-frequency runs of ADMX. Learn more about this experiment on the ADMX collaboration webpage.
MADMAX
MADMAX searches for the conversion of axions to photons in the regime around 100µeV (10-30GHz) using an array of multiple dielectric disks, called a "dielectric haloscope". MADMAX has many synergies with ADMX and BREAD and is a promising technology to probe the mass range between them. Learn more about this experiment on the MADMAX collaboration website.
Group Members
The axion group is just starting up! 🚀 For Harvard students: Contact knirck@fas.harvard.edu if you are interested in joining! We have several possibilities for undergraduate and graduate research projects. Not yet a Harvard student? Apply for Harvard College or the Harvard's physics graduate program.
Maja Benning
Alex Buzzi
I-see Jaidee
Stefan Knirck
knirck@fas.harvard.eduKnirck searches for axion dark matter using novel detectors. Axion dark matter searches are at the intersection between fundamental particle physics, astrophysics, photonics, and quantum sensing.
Ethan Lee
Estiven Lezama
Morgan Lynn
Juan Maldonado
Grant McIntyre
Jasmine Palma
Larom Segev
