Synergies in axion searches between MADMAX and BREAD

The QCD axion is a well-motivated hypothetical particle that could simultaneously explain the absence of CP violation in strong interactions and constitute the dark matter in our universe. Recent years have seen rapid advances in axion detection, driven by breakthroughs in quantum sensing technologies that enable unprecedented sensitivity. Two forefront experiments, Giga-BREAD at Harvard and MADMAX at the Max Planck Institute for Physics, pursue complementary approaches to detect axion-induced photons in the microwave range. By fostering collaboration between these efforts, we aim to accelerate progress through shared expertise and infrastructure. For instance, common data acquisition hardware has already been used for axion search runs, and both collaborations are converging toward mK operation with quantum-limited amplifiers. Our joint work focuses on knowledge exchange in dilution refrigerator setups, reflectivity and noise calibration techniques, and broadband quantum amplification, as well as exploring the integration of microwave photon counters to push sensitivity beyond the quantum limit. These synergies exemplify how transatlantic collaboration can catalyze the next generation of quantum-enhanced axion searches.