Speaker
Description
There is a general consensus that a large part of the matter and energy in the Universe is unknown. Well-established candidates for dark matter are axions or axion-like particles. While axions are expected, if they exist, to be everywhere in the galactic halo, their interaction with Standard Model particles is predicted to be very weak, and their mass (or frequency) is unknown. Hence, their detection requires broadband and ultrasensitive amplification and measurement techniques. Quantum sensing is appealing because it reaches the ultimate resolution, limited by the Heisenberg uncertainty principle. Pioneering experiments using quantum-limited microwave amplifiers based on superconducting circuit technology have explored the possibility of accelerating the axion dark-matter search. However, most of these experiments intrinsically rely on power measurements, which leads to a major limitation in the detection time. Furthermore, the standard microwave cavities used in these setups have limited frequency tunability, which restricts the accessible frequency range for axion detection. To overcome these limitations, we propose a paradigm for quantum-enhanced axion dark-matter search that does not rely on power measurements and offers wide frequency tunability. We propose to directly measure the axion amplitude and phase in an interferometric protocol at the quantum limit, using a nonlinear microwave cavity. In addition, we introduce gyromagnetic modes as wide-mass-range transducers for axion signals. We expect this scheme to offer an improvement of at least four orders of magnitude in the figure of merit and at least two orders of magnitude in mass (frequency) window with respect to standard haloscopes. Owing to its generality, our proposed protocol has the potential to speed up axion searches, as well as the detection for other cosmological signals such as the strongly red-shifted 21cm radiation from the early Universe. I will discuss the work done in Paris in this direction.