Extended Data Fig. 4: The finite-key secret key rate R versus the QBER.
From: Entanglement-based secure quantum cryptography over 1,120 kilometres
For the 3,100 s of data collected in our experiment, a QBER of below about 6.0% is required to produce a positive key. The previous work23 demonstrated a QBER of 8.1%, which is not sufficient to generate a secret key. In this work, a QBER of 4.5% and a secret key rate of 0.12 bits per second are demonstrated over 1,120 km. If one ignores the important finite-key effect, the QBER in ref. 23 is slightly lower than the well known asymptotic limit of 11% (ref. 43).
