Loop-Back Quantum Key Distribution (QKD) for Secure and Scalable Multi-Node Quantum Networks
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe Authors propose a Quantum Key Distribution (QKD) protocol. The proposed protocol involves a Loop-Back mechanism in ring topologies and bidirectional pulse propagation. They show that the protocol enables efficient key distribution by reducing the quantum bit error rate through a multi-pulse approach. The proposed method is compared to the other ones already discussed in the literature, and it is shown that the new approach could be a competitive proposal. As the Loop-Back QKD relies solely on direct polarization transformations, it can provide reduced vulnerability to side-channel attacks. In effect, the proposed design could enhance the robustness of proposed systems against a variety of unwanted external factors. The authors believe that the Loop-Back QKD protocol can accommodate an arbitrary number of participants in a ring topology. Finally, one can state that the ideas proposed in the article are valid enough to be published.
The manuscript is well written in general. It involves an extended and thorough introduction to the topics considered there, making it accessible to readers who are not necessarily experts in the field. The article also provides a list of references that could be helpful in further studies. However, the paper needs some improvements. Thus, although the manuscript mentions other QKD protocols, a more detailed comparative analysis, including performance metrics (e.g., key generation rate, security level) between the Loop-Back QKD protocol and existing methods is necessary. Table 7, presented in the article, seems to be insufficient. Next, a discussion concerning the potential limitations of the Loop-Back QKD protocol in real-world scenarios is highly desirable. So finally, one can state that the submitted article could be accepted after a minor revision of the abovementioned points.
Author Response
We sincerely appreciate the time and effort that the reviewers have put into evaluating our manuscript. Their insightful comments and constructive suggestions have significantly improved our work. In the attached file, we provide detailed responses to each comment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper proposed Loop-Back QKD protocol supporting two-part linear configurations and scalable multiuser ring topologies, reducing system complexity and QBER while enabling secure multiuser communication. Overall, it has certain innovation and research value. However, there are still some parts that need to be revised, as follows:
1. The paper merely proposed a new protocol, yet it lacks numerical simulations or experiments. It is recommended to add simulation results in a noise environment to comfirm the effectiveness of the protocol.
2. Table 6 and line 407: “While it is expected that increasing the number of pulses per round reduces the QBER from e to en ...”, however, en is greater than e. Is the author implying that the QBER reduces from e-1 to en? The meaning of n is not provided. Is n intended to represent the number of pulses? This requires clarication.
3. Line 419: the equation lacks numbering, and no references or derivation were provided.
4. The title of the table should be placed above the table, and the table does not follow the three-line format.
Author Response
We sincerely appreciate the time and effort that the reviewers have put into evaluating our manuscript. Their insightful comments and constructive suggestions have significantly improved our work. In the attached file, we provide detailed responses to each comment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsPlease find attached
Comments for author File: Comments.pdf
Author Response
We sincerely appreciate the time and effort that the reviewers have put into evaluating our manuscript. Their insightful comments and constructive suggestions have significantly improved our work. In the attached file, we provide detailed responses to each comment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThis is a really improved version as compared with the original. The authors have addressed all my remarks and suggestions.
