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DOE OSTI · 22283078

Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field

Dhakal, P.·Gurevich, A.
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Abstract

Measurements of the quality factor, Q, of Nb superconducting microwave resonators often show that Q increases by ≃10%–30% with increasing radio-frequency (rf) field, H, up to ∼15–20 mT. Recent high temperature heat treatments can amplify this rf field-induced increase of Q up to ≃50%–100% and extend it to much higher fields ≃100 mT, but the mechanisms of the enhancement of Q(H) remain unclear. Here, we suggest a method to reveal these mechanisms by measuring temperature dependencies of Q at different rf field amplitudes. We show that the increase of Q(H) does not come from a field dependent quasi-particles activation energy or residual resistance, but rather results from the smearing of the density of state by the rf field.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYACTIVATION ENERGYELECTRIC CONDUCTIVITYHEAT TREATMENTSMICROWAVE RADIATIONNIOBIUMQUALITY FACTORQUASI PARTICLESSUPERCONDUCTING CAVITY RESONATORSSUPERCONDUCTORSSURFACESTEMPERATURE DEPENDENCE

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Dhakal, P., Gurevich, A.. 2014-03-03. Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field. https://doi.org/10.1063/1.4867339

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