Quantum key distribution and 1 Gbps data encryption over a single fibre

Quantum-Classical Access Networks with Embedded Optical Wireless Links

“…The Raman noise generated by a strong classical signal spans over a wide range of frequencies, hence can populate the QKD receivers with unwanted signals [11]. Depending on the location of the QKD receiver, it may be affected by forward and backward scattered light [16].…”

“…Depending on the location of the QKD receiver, it may be affected by forward and backward scattered light [16]. For a classical signal with intensity I, at wavelength λ d , the Raman noise power at a QKD receiver with bandwidth ∆λ centered at wavelength λ q is given by [11] [12]…”

“…We have used here the results reported in [11] for λ d = 1550 nm, and have used the prescription in [16] to adapt it to any other wavelengths in the C band. The transmitted power I is also set to secure a BER of no more than 10 −9 for all data channels.…”

“…A hybrid quantumclassical network would, however, face certain challenges due to the nonlinear effects in optical fiber, such as four-wave mixing and Raman scattering [11]. The latter is regarded as the dominant source of background noise in such a combination [11].…”

“…A hybrid quantumclassical network would, however, face certain challenges due to the nonlinear effects in optical fiber, such as four-wave mixing and Raman scattering [11]. The latter is regarded as the dominant source of background noise in such a combination [11]. The impact of the Raman scattered light can be severe, because its spectrum can overlap with the frequency band of QKD channels, and, accordingly, it would increase the error probability at the QKD receivers.…”