Scientists have developed a groundbreaking two-stage dc-SQUID amplifier, specifically designed to enhance the sensitivity of magnetic detectors for celestial observations. This innovative device, crafted by Nan Li, Mengjie Song, Sixiao Hu, Wentao Wu, Songqing Liu, and Tangchong Kuang, features a unique four-cell input SQUID and a 100-cell series SQUID array. This design not only boosts signal gain but also effectively manages noise, achieving a remarkable magnetic flux noise level of approximately 100 pA/√Hz. This breakthrough is particularly significant for the next generation of experiments, especially the cosmic microwave background (CMB) polarization telescope operating in the 22-48GHz range, where highly sensitive readout systems are essential. The amplifier's performance is a testament to the team's meticulous design, incorporating asymmetric bias injection and dummy structures to enhance gradiometry, setting a new standard for low-noise readout electronics in TES detectors.
