Fig. 5

Quantum and classical transmission. a Secret key rate, bit error rate (BER), quantum bit error rate (QBER) and upper bound on the phase error (\({\phi }_{Z}^{u}\)) per core with co-propagating classical signals. Red dots represent the secret key rate per core. Blue diamonds and green downwards triangles are are the QBER and BER of the quantum and classical signals respectively. Yellow upwards triangles show the upper bound on the phase error. An average value of 1.7 Mbit s\({}^{-1}\)\(\pm\) 2.72 kbit s\({}^{-1}\), 0.82% \(\pm\) 0.0028% and 2.4E-10 was measured for the secret key rate, QBER and BER, respectively, while the upper bounds on the phase error show an average of 3.57% \(\pm\) 0.015%. Uncertainty values, computed as standard error of the mean, are not displayed as error bars are covered by the markers. b Secret key rate, QBER and upper bound on the phase error as a function of time. Red dots are the secret key rate measured in core number 37 for 30 min. Blue diamonds are the observed QBER in the same core and amount of time and yellow triangles the obtained upper bounds on the phase error. Average values of 1.52 Mbit s\({}^{-1}\)\(\pm\) 1.95 kbit s\({}^{-1}\) with 0.88% \(\pm\) 0.0023% QBER and 3.54% \(\pm\) 0.014% \({\phi }_{Z}^{u}\) is achieved. A total amount of 60 Gbit can thus be created over the multicore fibre in 30 min of measurement