This work describes some schemes using entangled photons for quantum key distribution which is fundamental of the new field called quantum communication. Depending on the circumstances, various protocols are used for the exchange of information.
Quantum communication represents a revolutionary advancement over classical information theory, which leverages unique quantum mechanics properties like entanglement to achieve unprecedented capabilities in secure and efficient information transmission. Unlike bits in classical communication, quantum communication utilizes qubits in superposition states, allowing for novel information storage and processing. Entanglement, a key quantum phenomenon, enables advanced protocols with enhanced security and processing power. This paper provides a comprehensive overview of quantum communication, emphasizing the role of entanglement in theoretical foundations, practical protocols, experimental progress, and security implications. It contrasts quantum communications potential applications with classical networks, identifying areas where entanglement offers significant advantages. The paper explores the fundamentals of quantum mechanics in communication, the physical realization of quantum information, and the formation of secure quantum networks through entanglement-based strategies like Quantum Key Distribution (QKD) and teleportation. It addresses the challenges of long-distance quantum communication, the role of quantum repeaters in scaling networks, and the conceptualization of interconnected quantum networks. Additionally, it discusses strides towards the Quantum Internet, Quantum Error-Correcting codes, and quantum cryptographys role in ensuring secure communication. By highlighting the role of entanglement, this paper aims to inspire further research and innovation in secure and efficient information exchange within quantum networks.
This paper investigates the core methods of information encoding and decoding within quantum networks, aiming to enhance both the efficiency and security of quantum information transmission. We explore various encoding schemes, including amplitude encoding, phase encoding, and polarization encoding, alongside their corresponding decoding strategies. The core mechanism relies on manipulating quantum states to represent and transmit information securely. Our research focuses on optimizing these processes to mitigate the effects of noise and loss, critical challenges in long-distance quantum communication. We delve into error correction techniques specifically tailored for quantum systems, such as quantum error correction codes (QECCs) and their application in decoding. Furthermore, we examine the role of quantum key distribution (QKD) protocols as a fundamental decoding process, highlighting the security aspects derived from the laws of quantum mechanics. The ultimate goal is to provide a comprehensive overview of the current state-of-the-art in quantum network information encoding and decoding, paving the way for future advancements in quantum communication technologies.
Quantum communication and quantum computation are novel methods of information transfer and information processing, all fundamentally based on the principles of quantum physics. The performances outdo their classical counterparts in many aspects [1,2]. In almost all quantum communication and quantum computation schemes, quantum entanglement [3] plays a decisive role. In essence, an entangled system can carry all information (e.g., on their polarization properties) only in their correlations, while no individual subsystem carries any information. This leads to correlations that are much stronger than classically allowed [89, 100], which is a powerful resource for information processing. It is therefore important to be able to generate, manipulate, and distribute entanglement as accurately and as efficiently as possible.
Abstract Multipartite quantum key distribution (QKD) is crucial for quantum communicating and may link massive private information to the complex quantum network protocols. In this paper, we tackle one of the difficulties in multipartite quantum communications by designing a quantum key distribution scheme with improved secret key rates. We suggest an entanglement-based tripartite continuous variable quantum key distribution (CVQKD) scheme for quantum network, where the source in the middle generates tripartite state and distributes the modes of the state to legitimate parties, respectively. We analyze the mutual information among the distributed modes of the tripartite state of protocols involving different attack strategies of the eavesdropper in varied circumstances. Numeric simulation results show that the CVQKD system enables the generations of secret keys against optimal coherent attacks.
Abstract In Quantum Key Distribution (QKD), two users extract a shared secret key using a quantum communication channel in the presence of an eavesdropper. Among QKD protocols, the ones based on Energy-Time (ET) entanglement of photons have been studied extensively due to their ability to generate high key rates from the arrival times of entangled photons. For the information reconciliation (IR) stage of ET-QKD protocols (where the users communicate using a classical channel in order to reconcile differences in their data), a scheme called multi-level coding (MLC) was proposed by Zhou et al. in prior work. The MLC scheme splits the raw key symbols into bit layers and utilizes binary Low-Density Parity-Check (LDPC) codes to encode each layer. Although binary LDPC codes are able to offer low complexity decoding for IR, they have poor error-correcting performance compared to their non-binary counterparts, thus leading to low key rates. Additionally, existing LDPC codes do not fully utilize the properties of the QKD channel to optimize the key rates. In this paper, we mitigate the above issues by proposing a flexible protocol for IR in ET-QKD systems called Non-Binary Multi-Level Coding NB-MLC(a) which is parameterized by a positive integer a. The NB-MLC(a) protocol is a generalization of the MLC scheme and utilizes NB-LDPC codes from a Galois field of size 2^a. We show that by using a small value of a, the NB-MLC(a) protocol significantly improves the key rate without much increase in complexity. To further improve the key rates of the NB-MLC(a) protocol, we propose i) a joint rate and degree distribution optimization (JRDO) algorithm to design the NB-LDPC codes for the protocol; ii) an interleaved decoding and communication (IDC) scheme to decode the different layers of the NB-MLC(a) protocol. The JRDO algorithm is designed to use the QKD channel information and we show that it results in a higher key rate than codes used in prior work. Additionally, the IDC scheme improves the key rate compared to the decoding and communication methods utilized previously in literature. Overall, the NB-MLC(a) protocol that uses JRDO LDPC codes and the IDC scheme results in a significant 40 − 60% improvement in key rates compared to prior work for ET-QKD systems.