Superconducting radio frequency

Superconducting radio frequency (SRF) science and technology involves the application of electrical superconductors to radio frequency devices. The absence of electrical resistivity in a superconducting material allows an RF resonator to obtain an extremely high quality factor, Q. For example, it is commonplace for a 1.3 GHz niobium SRF resonant cavity at 1.8 kelvins to obtain a quality factor of Q=5×1010.

Source: Wikipedia — Superconducting radio frequency (CC BY-SA 4.0)