Abstract This paper presents a comparative investigation of two quantum communication architectures – standard quantum key distribution (QKD) and semi-quantum key distribution (SQKD) – operating over noisy RF channels and enhanced with quantum phase estimation (QPE) feedback for phase noise mitigation. In QKD, both communicating parties are fully quantum-capable, while in SQKD, one party is restricted to limited classical-level quantum operations. The study evaluates performance under realistic noise models incorporating depolarizing noise, thermal relaxation, and Gaussian-distributed phase noise, examining the impact of QPE pilot configurations on phase tracking, residual error, and error rates. Simulation results reveal that while QPE feedback significantly improves robustness in both architectures, the SQKD configuration exhibits slower convergence, higher residual errors, and more variable key error rates due to the classical party’s limited corrective capabilities. These findings highlight the trade-offs between hardware complexity and performance in quantum-secured RF communication systems.
Abstract This paper presents a comparative investigation of two quantum communication architectures – standard quantum key distribution (QKD) and semi-quantum key distribution (SQKD) – operating over noisy RF channels and enhanced with quantum phase estimation (QPE) feedback for phase noise mitigation. In QKD, both communicating parties are fully quantum-capable, while in SQKD, one party is restricted to limited classical-level quantum operations. The study evaluates performance under realistic noise models incorporating depolarizing noise, thermal relaxation, and Gaussian-distributed phase noise, examining the impact of QPE pilot configurations on phase tracking, residual error, and error rates. Simulation results reveal that while QPE feedback significantly improves robustness in both architectures, the SQKD configuration exhibits slower convergence, higher residual errors, and more variable key error rates due to the classical party’s limited corrective capabilities. These findings highlight the trade-offs between hardware complexity and performance in quantum-secured RF communication systems.
Semiquantum key distribution protocols are designed to allow two parties to establish a shared secret key, secure against an all-powerful adversary, even when one of the users is restricted to measuring and preparing quantum states in one single basis. While interesting from a theoretical standpoint, these protocols have the disadvantage that a two-way quantum communication channel is necessary which generally limits their theoretical efficiency and noise tolerance. In this paper, we construct a semiquantum key distribution (SQKD) protocol which actually takes advantage of this necessary two-way channel, and, after performing an information theoretic security analysis against collective attacks, we show it is able to tolerate a channel noise level higher than any prior SQKD protocol to date. We also compare the noise tolerance of our protocol to other two-way fully quantum protocols, along with BB84 with classical advantage distillation. We also comment on some practical issues involving semiquantum key distribution (in particular, concerning the potential complexity in physical implementation of our protocol as compared with other standard QKD protocols). Finally, we develop techniques that can be applied to the security analysis of other (S)QKD protocols reliant on a two-way quantum communication channel.
Most prior semi-quantum key distribution (SQKD) protocols are designed in the context of qubits. In this paper, we proposed an SQKD protocol using ([Formula: see text]+1) quantum states in two mutually unbiased bases in the context of qudits without invoking the classical party’s measurement capability. It not only decreases the quantum states sent by quantum party by half, but also improves the efficiency of key rate than qubits do. To prove the security of present protocol, we first illustrate that the present protocol is completely robust, and then prove its unconditional security from information theoretical perspective by computing its key rate and noise tolerance against cloning-based individual attack. The unconditional security proof demonstrates that the higher dimension of quantum system is, the higher key rate can be obtained and the higher noise tolerance is allowed in depolarization channel.
Quantum computing poses significant threats to conventional cryptographic techniques such as RSA and AES, motivating the need for quantum secure communication methods. Quantum Key Distribution (QKD) offers information theoretic security based on fundamental quantum principles. This paper presents a simulation-based analysis of well-known QKD protocols, namely BB84, B92, and E91, using the IBM Qiskit framework. Realistic quantum channel effects, including noise, decoherence, and eavesdropping, are modeled to evaluate protocol performance. Key metrics such as error rate, secret key generation, and security characteristics are analyzed and compared. The study highlights practical challenges in QKD implementation, including hardware limitations and channel losses, and discusses insights toward scalable and robust quantum communication systems. The results support the feasibility of QKD as a promising solution for secure communication in the quantum era.
ABSTRACT Quantum key distribution (QKD) protocols are techniques that use the laws of quantum physics to safely distribute cryptographic keys. QKD protocols are able to identify attempts at eavesdropping during the distribution of keys, possibly providing a better level of security than traditional encryption. We present a comparative evaluation of the three QKD protocols, namely, BB84, E91 and an enhanced BB84 (EBB84) with the goal of identifying the best balance between security and efficiency for practical quantum communication systems. Motivated by the growing need for quantum‐resistant cryptography, extensive simulations in the Qiskit framework under both ideal and plausible noisy conditions is conducted, including depolarising, thermal relaxation, Pauli, amplitude damping and phase damping noise models. For each protocol, key lengths are varied from 200 to 3000 bits and, where relevant, simulated intercept–resend attacks to assess resilience against eavesdropping. The key performance metrics, QBER for BB84/EBB84 and the CHSH inequality parameter for E91 are computed over 50 iterations per scenario to ensure statistical robustness. The analysis reveals distinct trade‐offs: EBB84 achieves superior early eavesdropper detection at short key lengths, whereas differences between BB84 and EBB84 diminishes as key lengths increases; E91 maintains strong entanglement‐based security but is more sensitive to certain noise types. Regression analysis confirms that depolarising and amplitude damping noise most strongly influence QBER and CHSH degradation, whereas key length has a secondary effect. These findings mark the importance of adaptive key management and noise mitigation strategies and offer guidelines for integrating QKD into emerging network architectures such as SDN, 5G, and 6G.
Quantum key distribution (QKD) relies on the precise control and optimization of quantum states for enhanced secure communication. This study focuses on optimizing quantum state evolution through external control fields while minimizing decoherence and energy consumption. The key challenge addressed in this research is the trade-off between achieving high fidelity in quantum state transitions while reducing the environmental loss impact, which significantly affect QKD performance. The study employs a mathematical framework based on the quantum master equation, incorporating system Hamiltonians, control Hamiltonians, and loss functions to model quantum state evolution. Optimization is achieved using an optimal control functional that balances fidelity and energy consumption. Additionally, key generation rate maximization, quantum error correction strategies, and channel loss modeling are incorporated to enhance QKD efficiency. Numerical simulations evaluate the secure key generation rate, error mitigation, and fidelity of quantum states over time. Results demonstrate that at an initial quantum state value of 0.50, the system undergoes an oscillatory decay, stabilizing near zero at t=10, indicating the impact of decoherence. Secure key generation analysis reveals that with an error rate of 0.1, the key rate is maximized at 0.72, but declines sharply to nearly zero when the error rate exceeds 0.5. Fidelity measurements indicate an exponential decline, starting at 1.0 at T=0T = 0 and reducing to approximately 0.61 at T=50T = 50 and 0.37 at T=100T = 100, reflecting the challenges of maintaining quantum coherence. Error correction strategies successfully mitigate errors, achieving a quantum error correction rate of nearly 99% in optimal conditions. The findings support policies aimed at enhancing quantum communication reliability by emphasizing robust error correction methods, efficient energy management, and adaptive control strategies to counteract decoherence. Future work should explore real-time adaptive optimization frameworks to further enhance QKD performance under varying noise conditions.
Key generation is one of the basic techniques used to realize secure channels in this digital world. This article compares both Quantum Key Distribution (QKD) and Physical Layer Key Generation (PLKG). While QKD can give information-theoretic security by invoking principles of quantum mechanics, PLKG is based on exploiting inherent randomness and reciprocity in wireless channels to extract the key. This study, through simulations, provides a comparative analysis of the security and performance aspects of QKD and PLKG against key rate, error rate, bandwidth, channel loss, and Signal-to-Noise Ratio (SNR). The results demonstrate strong trade-offs between QKD and PLKG in terms of security, practicality, and efficiency, with QKD bringing better guarantees for security but both inherently limited in terms of distance and key rate. On the other hand, PLKG is more readily deployable with higher key rates, based on computational security assumptions. This work provides practical guidelines concerning the applicability of both approaches for specific communication applications based on system requirements for communication security.