Quasiparticle relaxation in high Q superconducting resonators

We present measurements of the quasiparticle relaxation time in Ta superconducting films shaped as planar resonators using the response of the complex conductivity to photon flux. These films have been implanted with magnetic (Mn) as well as non-magnetic atoms (Al). We find a significant decrease of the relaxation time with increasing impurity concentration for both cases, observing a reduction of the low temperature relaxation time, from 25 μs to 10 μs when implanting 100 ppm Mn. This indicates that impurities enhance quasiparticle relaxation in superconductors, regardless of their magnetic moment.