Abstract
Quantum key distribution (QKD) is regarded as an alternative to traditional cryptography methods for securing data communication by quantum mechanics rather than computational complexity. Towards the massive deployment of QKD, embedding it with the telecommunication system is crucially important. Homogenous optical multi-core fibers (MCFs) compatible with spatial division multiplexing (SDM) are essential components for the next-generation optical communication infrastructure, which provides a big potential for co-existence of optical telecommunication systems and QKD. However, the QKD channel is extremely vulnerable due to the fact that the quantum states can be annihilated by noise during signal propagation. Thus, investigation of telecom compatibility for QKD co-existing with high-speed classical communication in SDM transmission media is needed. In this paper, we present analytical models of the noise sources in QKD links over heterogeneous MCFs. Spontaneous Raman scattering and inter-core crosstalk are experimentally characterized over spans of MCFs with different refractive index profiles, emulating shared telecom traffic conditions. Lower bounds for the secret key rates and quantum bit error rate (QBER) due to different core/wavelength allocation are obtained to validate intra- and inter-core co-existence of QKD and classical telecommunication.
Highlights
Over previous years, data traffic has been continuously experiencing an exponential growth across the globe [1]
We investigate the telecom compatibility of Quantum key distribution (QKD) classical transmission over multi-core fibers (MCFs) by: 1) First, recording the photon leakage coming from the classical channels located at different wavelengths and/or cores into the quantum channel; 2) Adding the measured photon leakage to the total noise of a QKD system, and, calculating the lower bound for the secret key rate (SKR) shared between the sender (Alice) and receiver (Bob) after the postprocessing; and
We experimentally characterize the penalty for a QKD link over both TA- and untrenched MCF (UT-MCF) with the presence of beyond 100 Gbps classical communication signals per wavelength used for high-speed data transmission [29]
Summary
Data traffic has been continuously experiencing an exponential growth across the globe [1]. It is reported that when the quantum channel uses a dedicated core of MCF, network operators can avoid the noise generated by inter-core crosstalk by assigning the wavelengths lying in the guard-band between the classical data channels to the quantum signals [26]. In this paper, based on the experimental characterization in [29], we 1) report the analytical models of the two main noise sources in MCF fibers for QKD, i.e., inter-core crosstalk (XT) and intra-core spotaneous Raman scattering (SRS); and 2) provide a lower-bound estimation for the QKD link performance over two types of SDM fibers, considering both intra- and inter-core coexistence with high-speed data channels
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