Microwave Kinetic Inductance Detector Made of Molecular Beam Epitaxy (MBE)-Grown MgB2 Film

We present a MgB₂-based Microwave Kinetic Inductance Detector (MKID) featuring a quality factor Q_i ~ 10⁵ and noise equivalent power NEP ~ 10^-14 W/Hz at 2 K. In comparison to YBCO-based MKIDs, the MgB₂ detector shows greater sensitivity to both temperature and magnetic field, a result of its two-gap nature and relatively low critical Hc2 field. Our data indicate that MgB₂ is more advantageous for MKID applications at temperatures lower than 3 K.