  Superconducting terahertz (THz) metamaterial (MM) made from superconducting
Nb film has been investigated using a continuous-wave THz spectroscopy with a
superconducting split-coil magnet. The obtained quality factors of the resonant
modes at 132 GHz and 450 GHz are about three times as large as those calculated
for a metal THz MM operating at 1 K, which indicates that superconducting THz
MM is a very nice candidate to achieve low loss performance. In addition, the
magnetic field-tuning on superconducting THz MM is also demonstrated, which
offer an alternative tuning method apart from the existed electric, optical and
thermal tuning on THz MM.
