Optimized Quantum Key Distribution (QKD) protocols revolutionize the cyber security by leveraging the quantum phenomenon for development of unbreakable security. Configurable quantum networks are necessary for accessible quantum applications amongst multiple users. Quantum key distribution is particularly interesting because of the many ways in which the key exchange can be carried out. Keys can be exchanged by encoding the key into a weak photon source using classical methods, or the keys can be exchanged using pairs of photons entangled at the source, or the keys can even be exchanged by encoding with classical hardware at the source with an entangling measurement which occurs at the photons destination. Each type of quantum key exchange has its own requirements that must be met for point-to-point implementations which makes it exceedingly difficult to implement multi-node quantum networks. We propose a programmable network model to time encoded quantum key distribution; this version of QKD sends entangled photons to two users and the hardware is setup such that the relative time shift in the coincident photons encodes which measurement basis was used. The protocols were first simulated by modifying previous software which used the CHP quantum simulator, and then a point-to-point key exchange was setup in hardware to demonstrate the time encoding aspects of the protocol.
Optimized Quantum Key Distribution (QKD) protocols revolutionize the cyber security by leveraging the quantum phenomenon for development of unbreakable security. Configurable quantum networks are necessary for accessible quantum applications amongst multiple users. Quantum key distribution is particularly interesting because of the many ways in which the key exchange can be carried out. Keys can be exchanged by encoding the key into a weak photon source using classical methods, or the keys can be exchanged using pairs of photons entangled at the source, or the keys can even be exchanged by encoding with classical hardware at the source with an entangling measurement which occurs at the photons destination. Each type of quantum key exchange has its own requirements that must be met for point-to-point implementations which makes it exceedingly difficult to implement multi-node quantum networks. We propose a programmable network model to time encoded quantum key distribution; this version of QKD sends entangled photons to two users and the hardware is setup such that the relative time shift in the coincident photons encodes which measurement basis was used. The protocols were first simulated by modifying previous software which used the CHP quantum simulator, and then a point-to-point key exchange was setup in hardware to demonstrate the time encoding aspects of the protocol.
Optimized Quantum Key Distribution (QKD) protocols revolutionize the cyber security by leveraging the quantum phenomenon for development of unbreakable security. Configurable quantum networks are necessary for accessible quantum applications amongst multiple users. Quantum key distribution is particularly interesting because of the many ways in which the key exchange can be carried out. Keys can be exchanged by encoding the key into a weak photon source using classical methods, or the keys can be exchanged using pairs of photons entangled at the source, or the keys can even be exchanged by encoding with classical hardware at the source with an entangling measurement which occurs at the photons destination. Each type of quantum key exchange has its own requirements that must be met for point-to-point implementations which makes it exceedingly difficult to implement multi-node quantum networks. We propose a programmable network model to time encoded quantum key distribution; this version of QKD sends entangled photons to two users and the hardware is setup such that the relative time shift in the coincident photons encodes which measurement basis was used. The protocols were first simulated by modifying previous software which used the CHP quantum simulator, and then a point-to-point key exchange was setup in hardware to demonstrate the time encoding aspects of the protocol.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor�s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates advancements in hardware, standardization, and hybrid cryptographic strategies for widespread adoption.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor’s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates
Quantum key distribution (QKD) is a technology that allows two users to communicate with theoretically perfect security using standard optical fibres. This is possible by transmitting the key on single photons, meaning a measurement by an eavesdropper disturbs the system in a way observable to the legitimate parties. The technology has advanced since the first protocol proposed in 1984, to the stage where there are now many protocols that can be experimentally implemented. These protocols have allowed secure keys to be generated over distances greater than 400 km and with secure key rates over 10 Mbit/s. In a metropolitan QKD network, it would be desirable for as many users to be connected as possible. Unfortunately, each protocol comes with different requirements on the transmitter and receiver. Even within a single protocol, different clock rates can require individualised transmitter and receiver hardware. This prohibits users from communicating with all receivers, unless they have complex transmitters with hardware for many protocols. This thesis develops a transmitter for practical QKD that is able to adapt to a number of different protocols with no changes to the hardware. The transmitter works using optical injection locking, where a pulse preparation laser adopts the phase of a phase preparation laser. Controlling the phase and intensity of the pulses in this way removes the side channel ordinarily present with direct modulation, in that the phase, intensity and frequency simultaneously change in response to an applied current. The cavity-enhanced electro-optic effect allows for the first demonstration of sub-volt half-wave phase modulation at high clock rates. The transmitter successfully demonstrates phase encoding, intensity encoding and on-demand phase randomisation. This allows for the experimental realisation and direct comparison of different QKD protocols, including one that has never before been implemented due to experimental complexity. A stable intensity modulator is also developed, based on a Sagnac interferometer. This removes a side channel in QKD systems and integrates well with the directly-modulated quantum transmitter. This development also means that the transmitter can implement all current two-party QKD protocols based on weak coherent pulses. The transmitter has the potential to become the standard transmitter for future quantum communication networks due to its stability, versatility and power efficiency. The design could also be demonstrated on a photonic chip, making it compact enough to fit in small transmitter units.
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.
Quantum key distribution, which allows two distant parties to share an unconditionally secure cryptographic key, promises to play an important role in the future of communication. For this reason such technique has attracted many theoretical and experimental efforts, thus becoming one of the most prominent quantum technologies of the last decades. The security of the key relies on quantum mechanics and therefore requires the users to be capable of performing quantum operations, such as state preparation or measurements in multiple bases. A natural question is whether and to what extent these requirements can be relaxed and the quantum capabilities of the users reduced. Here we demonstrate a novel quantum key distribution scheme, where users are fully classical. In our protocol, the quantum operations are performed by an untrusted third party acting as a server, which gives the users access to a superimposed single photon, and the key exchange is achieved via interaction-free measurements on the shared state. We also provide a full security proof of the protocol by computing the secret key rate in the realistic scenario of finite-resources, as well as practical experimental conditions of imperfect photon source and detectors. Our approach deepens the understanding of the fundamental principles underlying quantum key distribution and, at the same time, opens up new interesting possibilities for quantum cryptography networks