Prospects of Chip-Based Multi-Protocol Quantum Key Distribution Transceivers

Quantum communications enable the transmission of information in a secure way that is ensured by the laws of quantum physics. Current quantum-safe communication systems are based on quantum key distribution (QKD) technology at their core. In the most recent years, a remarkable effort has been put into practical implementations of QKD with a focus on their integration into classical optical networks, some of which are becoming commercially available. However, even with the ongoing development of QKD systems, there are efforts toward their miniaturization, power efficiency improvement, and enhancement of their flexibility and functionality.In this paper, we outline major QKD protocols and review recent advances in QKD systems based on photonic integrated circuits. Finally, we will discuss the potential feasibility of multi-protocol QKD chips leveraging the advantages of different protocols in one solution

Securing Communication with Quantum Key Distribution:Implications and Impact on Network Performance

With a fully functional point-to-point quantum key distribution link, we demonstrate secret key retrieval by a pair of encryptors and investigate how their addition impacts key network performance indicators on a 10 Gbit/s data channel

100G shortwave wavelength division multiplexing solutions for multimode fiber data links

We investigate an alternative 100G solution for optical short-range data center links. The presented solution adopts wavelength division multiplexing technology to transmit four channels of 25G over a multimode fiber. A comparative performance analysis of the wavelength-grid selection for the wavelength division multiplexing data link is reported. The analysis includes transmissions over standard optical multimode fiber (OM): OM2, OM3 and OM4

Challenges in Polybinary Modulation for Bandwidth Limited Optical Links

Optical links using traditional modulation formats are reaching a plateau in terms of capacity, mainly due to bandwidth limitations in the devices employed at the transmitter and receivers. Advanced modulation formats, which boost the spectral efficiency, provide a smooth migration path towards effectively increase the available capacity. Advanced modulation formats however require digitalization of the signals and digital signal processing blocks to both generate and recover the data. There is therefore a trade-off in terms of efficiency gain vs complexity. Polybinary modulation, a generalized form of partial response modulation, employs simple codification and filtering at the transmitter to drastically increase the spectral efficiency. At the receiver side, polybinary modulation requires low complexity direct detection and very little digital signal processing. This paper provides an overview of the current research status of the key building blocks in polybinary systems. The results clearly show how polybinary modulation effectively reduces the bandwidth requirements on optical links while providing high spectral efficiency

Replicability of a Millimeter-Wave Microstrip Bandpass Filter using Parallel Coupled Lines

Replicability of filters is critical especially at millimeter-wave (mm-wave) frequencies, as a manufacturing error of a few tens of microns can significantly shift the frequency response in this range and lumped elements are not available at these frequencies. In this paper, seven replicas of a mm-wave coupled-line 3 rd order bandpass filter (BPF) are fabricated and measured under the same test conditions. The filters are designed on a single lot 10 mil-thick Rogers RO4350B substrate. The smallest spacing is 109 μm and the smallest line width is 330 μm. Over seven replicas, the passband is from 34.8±0.2 to 38.1±0.1 GHz; the insertion loss is 3.44±0.32 dB; the typical return loss is 10.18±2.43 dB. The measurement results are in accordance with the EM simulation results. They show that the reflection parameters are relatively sensitive to manufacturing tolerances and connector realization, while the transmission parameters are robust to fabrication variations. This demonstrates a satisfactory manufacturing replicability of microstrip BPF in the Ka-band (26.5-40 GHz), in the scope of radar system design.The authors thank EU Horizon 2020 Marie Sklodowska-Curie ITN CELTA project (grant agreement no. 675683) for partial financial support, RAMMS project and DLR MIMIRAWE project funded by the Federal Ministry for Economic Affairs and Energy (grant number: 50RA1326) for partial financial support

Secure and Agile 6G Networking:Quantum and AI Enabling Technologies

This paper proposes a novel architecture for enabling ultra-fast and ultra-safe 6G networks that can support complex and challenging real-time applications based on four key enabling technologies: 1) performance prediction, 2) AI-enabled task offloading, 3) quantum machine learning, and 4) quantum-resistant communication. With the emergence of 6G applications where the real-time quality of experience is prioritized, AI-enabled task offloading leverages the benefits of edge computing. Moreover, the execution time of complex applications can be reduced by using quantum computers at the edge or in the cloud. In addition, by incorporating quantum key distribution and post-quantum cryptography, we can ensure the safety of mobile networks in the quantum computing era. Collectively, these technologies will provide ultra-fast and ultra-safe 6G networks, meeting the requirements of challenging real-time applications that were not supported in the previous generations, thus advancing the state of the art of mobile communication networks

From classical to quantum machine learning: survey on routing optimization in 6G software defined networking

The sixth generation (6G) of mobile networks will adopt on-demand self-reconfiguration to fulfill simultaneously stringent key performance indicators and overall optimization of usage of network resources. Such dynamic and flexible network management is made possible by Software Defined Networking (SDN) with a global view of the network, centralized control, and adaptable forwarding rules. Because of the complexity of 6G networks, Artificial Intelligence and its integration with SDN and Quantum Computing are considered prospective solutions to hard problems such as optimized routing in highly dynamic and complex networks. The main contribution of this survey is to present an in-depth study and analysis of recent research on the application of Reinforcement Learning (RL), Deep Reinforcement Learning (DRL), and Quantum Machine Learning (QML) techniques to address SDN routing challenges in 6G networks. Furthermore, the paper identifies and discusses open research questions in this domain. In summary, we conclude that there is a significant shift toward employing RL/DRL-based routing strategies in SDN networks, particularly over the past 3 years. Moreover, there is a huge interest in integrating QML techniques to tackle the complexity of routing in 6G networks. However, considerable work remains to be done in both approaches in order to accomplish thorough comparisons and synergies among various approaches and conduct meaningful evaluations using open datasets and different topologies

A device and method for generating a polybinary signal

The present disclosure relates to a method for generating an L-level polybinary signal, comprising the steps of: providing a baseband signal with a spectrum defined by a predefined frequency period, f p ; filtering the baseband signal using a low-pass filter having a pre-defined cut-off frequency, f c- o, and a preefined polynomial order, n, whereby the L-polybinary signal is generated; filtering the L-polybinary signal before or after it is generated, with at least one band-stop filter having a pre-defined center frequency, f c , and a pre-defined bandwidth, Δ, thereby isolating f p of the baseband signal. The present disclosure relates to a method for generating an L-level polybinary signal, comprising the steps of: providing a baseband signal with a spectrum defined by a predefined frequency period, f p ; filtering the baseband signal using a low-pass filter having a pre-defined cut-off frequency, f c- o, and a preefined polynomial order, n, whereby the L-polybinary signal is generated; filtering the L-polybinary signal before or after it is generated, with at least one band-stop filter having a pre-defined center frequency, f c , and a pre-defined bandwidth, Δ, thereby isolating f p of the baseband signal