Ultra-high bandwidth quantum secured data transmission

Abstract

Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

10-Mb/s Quantum Key Distribution

“…5) An EC implementation that has a low information leakage (f EC → 1); 6) A PA implementation that must be able to handle large dataset size to mitigate finite-size effects arising from statistical fluctuations in the measured quantities; 7) Finally, both EC and PA modules must have data throughput greater than the sifted key rate (f η d η sif t ). To achieve 10 Mb/s secure key rates would require EC/PA throughput of 40 Mb/s and sifting throughput of 50 MC/s, when considering typical experimental parameters found in previous QKD implementations [8].…”

“…Despite such a strict security parameter, the T12 protocol provides a typical secure key rate in excess of 1 Mb/s over an optical fibre length of 50 km [11]. Record rates were reported using this protocol for several distances up to 240 km [14], even in presence of the noise introduced by classical channels multiplexed with the quantum channel [8].…”

Universal random codes: capacity regions of the compound quantum multiple-access channel with one classical and one quantum sender

“…Developing coding schemes for such situations is technologically paramount importance, since presuming availability of a "dark fibre" for performing a transmission protocol is rarely feasible. This fact already became apparent as a limiting factor in recent attempts to use commercial fibre lines for quantum key distribution [20] commercial fibre lines are usually a valuable resource being shared by many users. Consequently, the rate as well as the performance each of the sending parties can achieve is in general strongly connected to the signal characteristics of other parties.…”

Modeling high quantum bit rate QKD systems over optical fiber

“…Record setting transmission distances over 300 km [12] and reaching 400 km [13] (not necessarily at the high secure key rates) were achieved using low loss fiber. Hence, low loss and low nonlinearity fibers are of interest when high bit rate classical and quantum channel transmission over the same fiber is of interest [14]. Some of the work cited above is permeated with the effort to find conditions under which the fiber can be used for both QKD and classical signal transmission simultaneously.…”