Fast tunable high Q-factor superconducting microwave resonators

摘要: We present fast tunable superconducting microwave resonators fabricated from planar NbN on a sapphire substrate. The $3\lambda/4$ wavelength are tuning fork shaped and tuned by passing dc current which controls the kinetic inductance of prongs. $\lambda/4$ section open end operates as an integrated impedance converter creates nearly perfect short for currents at terminal coupling points, thus preventing energy leakage through lines. measure internal quality factor $Q_{\rm int}>10{^{5}}$ over entire range. demonstrate range $> 3\%$ response times 20 ns maximum achievable detuning. Due to quasi-fractal design, resilient magnetic fields up 0.5 T.