Enhanced quantum sensitivity and coherence of symmetric magnetic clusters

The search for highly coherent degrees of freedom in noisy solid-state environments is a major challenge in condensed matter. In disordered dipolar systems, such as magnetically doped insulators, compact clusters of two-level systems (TLS) have recently been shown to have significantly longer coherence times than typical single TLS. Coupling weakly to their environment, they sense and probe its many-body dynamics through the induced dephasing. However, it has remained an open question whether further mechanisms exist that protect the coherence of such solid-state qubits. Here we show that symmetric clusters of few TLS couple even more weakly to their surroundings, making them highly sensitive quantum sensors of slow many-body dynamics. Furthermore, we explore their use as qubits for quantum information storage, detailing the techniques required for their preparation and manipulation. Our findings elucidate the role of symmetry in enhancing quantum coherence in disordered and noisy systems, opening a route toward a sensitive experimental probe of many-body quasi-localization dynamics as well as the development of quantum technologies in solid-state systems.