Schematic cross section of a copper tape worm of the first generation, with a soldered seam. The width of a ribbon with three twisted pairs is about .
Partially assembled superconducting filter. When fully assembled, several such filters are stacked and the aluminum bars shown in the picture are replaced by long copper bars connecting the filters. The brass parts in the center accommodate the capacitors.
Insertion loss of a filter prototype in a line at low frequencies at 300 and at with a superconducting core. Below the roll off, the data shows negligible dissipation. Above , the two measured curves converge. The peak in the data is due to an resonance of the capacitors and the line inductance. The inset shows the attenuation from at room temperature. Above about , the signal disappears in the noise floor of the network analyzer.
Insertion loss of short test pieces without discrete capacitors in a line at room temperature. The data have been scaled to a total length of assuming that the attenuation (i.e., ) decays exponentially with increasing length. The data from two pieces of different length collapse well and show a significantly higher attenuation than the model for a long line whose parameters have been chosen to match the scaled data below about . The inset shows the model for the complete filter using the parameters extracted from measurements. The ratio of the bosonic spectral densities at and for is shown for comparison in both plots.
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