SQUID-based microwave cavity search for dark-matter axions

Phys Rev Lett. 2010 Jan 29;104(4):041301. doi: 10.1103/PhysRevLett.104.041301. Epub 2010 Jan 28.


Axions in the microeV mass range are a plausible cold dark-matter candidate and may be detected by their conversion into microwave photons in a resonant cavity immersed in a static magnetic field. We report the first result from such an axion search using a superconducting first-stage amplifier (SQUID) replacing a conventional GaAs field-effect transistor amplifier. This experiment excludes KSVZ dark-matter axions with masses between 3.3 microeV and 3.53 microeV and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.