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Regular version of the site

Article

Protocol of measuring hot-spot correlation length for SNSPDs with near-unity detection efficiency

IEEE Transactions on Applied Superconductivity. 2019. Vol. 29. No. 5. P. 1-5.
M. Polyakova, Semenov A., Kovalyuk V., Ferrari S., Pernice W., G.N. Gol’tsman.

We present a simple quantum detector tomography
protocol, which allows, without ambiguities, to measure the twospot
detection efficiency and extract the hot-spot interaction length
of SNSPDs with unity intrinsic detection efficiency. We identify a
significant parasitic contribution to the measured two-spot efficiency,
related to an effect of the bias circuit, and find a way to rule
out this contribution during data post-processing and directly in
the experiment. From the data analysis for waveguide-integrated
SNSPD, we find signatures of the saturation of the two-spot efficiency
and hot-spot interaction length of order of 100 nm.