Improving Continuous Variable Quantum Secret Sharing with Weak Coherent States
Round 1
Reviewer 1 Report
The manuscript “Improving continuous variable quantum secret sharing with weak coherent states” by Y. Wang and coworkers contains an extended study of the mechanisms underpinning Quantum Secret Sharing (QSS) through continuous variable (CV) systems. Over against the discrete variable (DV) scenario, CV-QSS allows to overcome some puzzling aspects as low channel capacity and the difficulty in preparing single photons through the manipulation of coherent and squeezed states. Specifically, the manuscript by Y. Wang et al. (i) suggests a way to establish a Gaussian Modulated Coherent State (GMCS) based scheme for CV-QSS, (ii) shows how to set-up a (t,n) scheme for CV-QSS, and (iii) demonstrates the security of the GMCS-involved CV-QSS against various attacks, e.g. intercept-and-resend attack, and collective attack.
The results are interesting and seem correct. However, I think that some points can be extended and clarified to have the necessary impact on the field, hence to be published in Applied Science (MDPI). First of all, the sentence “Not only can they increase the channel capacity, but also they can be generated and operated by linear optical components” which has been inserted in the introduction of the manuscript can be confusing: squeezed light can be generated from coherent light through non-linear interactions (lithium niobite and periodically poled potassium titanyl phosphate). The authors can amend that sentence to improve the readability of the manuscript.
To make the manuscript understandable to a more large audience, I suggest the authors to be more pedagogical in introducing Section II (Figure I can be re-designed to be more clear). Here, Y. Wang et al. do not discuss the “role” of the laster (L) and the modulator (M) within the main text. The discussion inserted in Section IV is very interesting as it shows the relation between the Secure Key rate (bits/pulse) and the fiber length: the output of the analysis shows that the longer the fiber length, the more the influence of different kinds distribution of legitimate participants. While Figure IV and Figure V are clear, Figure III is not: the authors forgot to include the meaning of the different colours. Can the authors discuss how the plots change when varying the other parameters (e.g. the reconciliation efficiency and the attenuation coefficient)?
I greatly encourage the authors to address these points which, in my opinion, can increment the readability of the paper. If these points are overcome, I can recommend the publication of this work.
Author Response
Dear Reviewer 1,
Thank you very much for your careful and constructive advices. Those comments are all valuable and very helpful for revising and improving our paper, and with the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made some changes in the manuscript. Please refer to the revised paper and following answers.
For the detailed point-by-point response, please see them in attachment.
Thank you again.
With best regards,
Yours sincerely,
Yijun Wang, Bing Jia, Yun Mao, Xunlin Wu, Ying Guo
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors presented here a quantum-secret-sharing scheme based on Gaussian-modulated coherent states, which is interesting because such states are easily generated with current technology.
The point of this research is clear and motivated. Their results are convincing as well. I have just some minor comments.
1) I see that the authors did not specify which kinds of distributions they employed in Fig.3. I guess that this is because the figure clearly shows that the choice of the distribution does not affect the dependence of the secure-key-rate on the fiber length that much, however I would add this information for completeness.
2) In Eq.(4), I guess that j_{k} should be a subscript.
3) At the end of page 2, in the sentence "Finally, the quantum state of dealer can be expressed as..." there is a typo mistake in the expression of the state.
Finally, I have some observations on the English.
1) More than once, the authors write "amplitude and the phase quadratures" (in particular at the end of page 2 and at point 3 of the subsection "Preparation stage"), but I think it should be "the amplitude and phase quadratures".
2) In Fig. 1 and 2, the authors write "laster", but I assume they meant "laser".
3) At point 3 of the subsection "Preparation stage", I think that the expression "Each of remained participant" should be "Each of the remained participants" and that, in the following, where the authors say "at the same" they meant "at the same time".
4) At page 8, I guess that the second and third sentences under the Table should be a unique sentence.
Provided that the authors comment these observations and correct what they think should be corrected, I suggest this article for publication.
Author Response
Dear Reviewer,
Thank you very much for your careful and constructive advices. Those comments are all valuable and very helpful for revising and improving our paper, and with the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made some changes in the manuscript. Please refer to the revised paper and following answers.
For the point-by-point response, please see them in attachment.
Thank you again.
With best regards,
Yours sincerely,
Yijun Wang, Bing Jia, Yun Mao, Xunlin Wu, Ying Guo
Author Response File: 
Author Response.pdf
