arXiv:2505.24851 · IEEE Transactions on Quantum Engineering
Realistic Quantum Network Simulation for Experimental BBM92 Key Distribution
Michelle Chalupnik, Brian Doolittle, Suparna Seshadri, Eric Brown, Keith Kenemer, Daniel Winton, Daniel Sanchez-Rosales, Matthew Skrzypczyk, Cara Alexander, Eric P. Ostby, Michael Cubeddu
Quantum key distribution (QKD) can provide secure key material between two parties without relying on assumptions about the computational power of an eavesdropper. QKD is performed over quantum links and quantum networks, systems which are resource-intensive to deploy and maintain. To evaluate and optimize performance prior to, during, and after deployment, accurate simulations with attention to physical realism are necessary. Quantum network simulators can simulate a variety of quantum and classical protocols and can assist in quantum network design and optimization by offering realism and flexibility beyond mathematical models which rely on simplifying assumptions and can be intractable to solve as network complexity increases. We use a versatile discrete event quantum network simulator to simulate the entanglement-based QKD protocol BBM92 and compare it to our experimental implementation and to existing theory. We find the discrete event quantum network simulator can match experimental key rates and error rates with a lower mean squared error than analytical theory. Furthermore, we simulate secure key rates in a repeater key distribution scenario for which no experimental implementations exist and find agreement between simulation and analytical theory. Hence, we demonstrate discrete event simulators can meet needs in quantum network simulations which cannot be filled solely by experiment or theory: discrete event simulators can accurately simulate QKD protocols and match experiments in regimes where theoretical models may require more simplifying assumptions, and they can match theoretical models in the opposite scenario where experiments have not yet been performed but theoretical models exist.
Quantum key distribution (QKD) can provide secure key material between two parties without relying on assumptions about the computational power of an eavesdropper. QKD is performed over quantum links and quantum networks, systems which are resource-intensive to deploy and maintain. To evaluate and optimize performance prior to, during, and after deployment, accurate simulations with attention to physical realism are necessary. Quantum network simulators can simulate a variety of quantum and classical protocols and can assist in quantum network design and optimization by offering realism and flexibility beyond mathematical models which rely on simplifying assumptions and can be intractable to solve as network complexity increases. We use a versatile discrete event quantum network simulator to simulate the entanglement-based QKD protocol BBM92 and compare it to our experimental implementation and to existing theory. We find the discrete event quantum network simulator can match experimental key rates and error rates with a lower mean squared error than analytical theory. Furthermore, we simulate secure key rates in a repeater key distribution scenario for which no experimental implementations exist and find agreement between simulation and analytical theory. Hence, we demonstrate discrete event simulators can meet needs in quantum network simulations which cannot be filled solely by experiment or theory: discrete event simulators can accurately simulate QKD protocols and match experiments in regimes where theoretical models may require more simplifying assumptions, and they can match theoretical models in the opposite scenario where experiments have not yet been performed but theoretical models exist.
Quantum Key Distribution (QKD) is a foundational method for the secure generation and distribution of cryptographic keys between network nodes, relying on quantum mechanical principles to provide information-theoretic security. As quantum computing continues to advance, the development of quantum communication networks requires the implementation of complex and secure architectures. However, the deployment of such networks demands considerable financial, technical, and human resources. In this context, simulation tools are essential, as they enable researchers to validate theoretical models, optimize network design, and identify potential vulnerabilities without the need for costly physical infrastructure. The goal of the research was to evaluate the efficiency and accuracy of QNET simulation tool by comparing the outcomes of developed simulation models with empirical data from real QKD networks. While the results in some cases closely aligned indicating a high level of accuracy in modeling QKD networks noticeable discrepancies were observed in certain scenarios. Such an approach not only facilitates more accurate modeling and planning but also promotes the development of scalable, cost effective, and secure quantum communication systems.
The promise of unconditional security in the Quantum Key Distribution (QKD) depends on the availability of an authenticated classical channel. However, practical implementations often overlook this requirement or rely on computational assumptions that compromise long-term security. To overcome these challenges, this paper presents Entanglement-Based Authenticated Quantum Key Distribution (EAQKD), a novel protocol that addresses critical security and practical limitations in quantum cryptographic key exchange. Our approach integrates quantum entanglement distribution with information-theoretic authentication. We evaluate EAQKD's performance through a comprehensive discrete-event simulation framework modeled on realistic channel characteristics and experimental device parameters. Our modeling incorporates parameters from practical quantum optics setups, including SPDC entanglement sources, superconducting nanowire detectors, and fiber channel imperfections. Our results show quantum bit error rates consistently below the 11% security threshold (ranging from 1.86% at 10 km to 9.27% at 200 km), with secure key rates achieving 1.12×105 bits/s at short distances and maintaining practical rates of 9.8 bits/s at 200 km. When integrated with quantum repeater architectures, our analysis projects that EAQKD can extend secure communication beyond 500 km while providing information-theoretic security guarantees. Comparative analysis against the BB84, E91, and Twin-Field QKD protocols demonstrates EAQKD's superior balance of security, practical performance, and implementation robustness. This work advances quantum cryptography by providing a rigorously analyzed engineering reference for secure key distribution in future quantum communication networks.
Quantum key distribution (QKD) has been promoted as a means for secure communications. Although QKD has been widely implemented in many urban fiber networks, the large-scale deployment of QKD remains challenging. Today, researchers extensively conduct simulation-based evaluations for their designs and applications of large-scale QKD networks for cost efficiency. However, the existing discrete-event simulators offer models for QKD hardware and protocols based on sequential event execution, which limits the scale of the experiments. In this work, we explore parallel simulation of QKD networks to address this issue. Our contributions lay in the exploration of QKD network characteristics to be leveraged for parallel simulation as well as the development of a parallel simulation framework for QKD networks. We also investigate three techniques to improve the simulation performance including (1) a ladder queue based event list, (2) memoization for computationally intensive quantum state transformation information, and (3) optimization of the network partition scheme for workload balance. The experimental results show that our parallel simulator is 10 times faster than a sequential simulator when simulating a 128-node QKD network. Our linear-regression-based network partition scheme can further accelerate the simulation experiments up to two times over using a randomized network partition scheme.
Quantum Key Distribution (QKD) enables two parties to securely share encryption keys by leveraging the principles of quantum mechanics, offering protection against eavesdropping. In practical implementations, QKD systems often rely on a layered architecture where a key manager stores secret key material in a buffer and delivers it to higher communication layers as needed. However, this buffer can be depleted under high demand, requiring efficient replenishment strategies that minimize resource waste. Given the importance of optimizing time and resources in quantum cryptography protocols, we introduce a variable-length adaptation of the BB84 protocol designed to meet user-defined output key length constraints in non-ideal scenarios. We present a method for dynamically configuring the protocol’s initial parameters to generate secret keys of a desired length. To validate our approach, we developed simulation tools to model general QKD networks and discrete-variable protocols. These tools were used to implement and evaluate our strategies, which were developed within the BB84 framework but can be extended to other QKD protocols under reasonable assumptions. The results highlight their usefulness in optimizing quantum resource usage and supporting key management, contributing to the long-term goal of scaling and strengthening secure quantum networks.
Quantum Key Distribution (QKD), based on the laws of physics rather than the computational \ncomplexity of mathematical problems, provides a secure way of establishing symmetrical binary \nkeys between two geographically distant users. The keys are secure from eavesdropping during \ntransmission and QKD ensures that any third party’s knowledge of the key is reduced to a \nminimum. In recent years, a noticeable progress in the development of quantum equipment has \nbeen reflected through a number of successful demonstrations of QKD technology. While they \nshow the great achievements of QKD, many practical difficulties still need to be resolved, such as \nto provide better service differentiation. These networks are characterized as being multihop in \nnature where the consumption key rate is often higher than the charging key rate, which means that \nthe links are available for a limited period of time only. Such features impose several challenges \non the effective modeling and evaluation of reliability as well as finding appropriate Quality \nof Service (QoS) solution. This thesis focuses on research in the field of QKD for securing \nreal-time communication by supporting QoS in QKD networks including a novel QoS model \nand novel distributed reactive routing protocol to achieve high-level scalability and minimize the \nconsumption of key material used for securing routing data. \nAs research in QKD networks grows larger and more complex, the need for highly accurate and \nscalable simulation technologies becomes important to assess the practical feasibility and foresee \ndifficulties in the practical implementation of theoretical achievements. Due to the specificity of \nQKD link which requires optical/quantum and Internet connection between the network nodes, it \nis very costly to deploy a complete testbed containing multiple network hosts and links to validate \nand verify a certain network algorithm or protocol. The network simulators in these circumstances \nsave a lot of money and time in accomplishing such task. A simulation environment offers the \ncreation of complex network topologies, a high degree of control and repeatable experiments, \nwhich in turn allows researchers to conduct exactly the same experiments and confirm their results. \nThis thesis describes the design and implementation of QKD network simulation module which \nwas developed in the network simulator of version 3 (NS-3). The module supports simulation \nof QKD network in overlay mode or in a single TCP/IP mode. Therefore, it can be used for \nsimulation of other network technologies regardless of QKD. \nImplemented simulation model was used for verification of proposed QoS solution. A number \nof simulations were performed. The obtained data have confirmed the primary thesis of this study, \nthat it is possible to use real-time applications in QKD networks.
With the significantly growing investment in quantum communi-cations, quantum key distribution (QKD), as a key application toshare a security key between two remote parties, has been deployedin urban areas and even at a continental scale. To meet the designrequirements of QKD on a quantum communication network, todayresearchers extensively conduct simulation-based evaluations in ad-dition to physical experiments for cost efficiency. A practical QKDsystem must be implemented on a large scale via a network, notjust between a few pairs of users. Existing discrete-event simulatorsoffer models for QKD hardware and protocols based on sequentialexecution. In this work, we investigate the parallel simulation ofQKD networks for scalability enhancement. Our contributions layin the exploration of QKD network characteristics to be leveragedfor parallel simulation. We also develop a parallel simulator forQKD networks with an optimized scheme for network partition.Experimental results show that to simulate a 64-node QKD net-work, our parallel simulator can complete the experiment 9 timesfaster than a sequential simulator running on the same machine.Our linear-regression-based network partition scheme can furtheraccelerate the simulation experiments up to two times than using arandomized network partition scheme.