# Two-Party Quantum Private Comparison Protocol Based on Rotational Encryption
## 7 Conclusions  
In conclusion, we propose a two-party quantum private comparison (QPC) protocol that leverages single photons and rotational encryption to ensure the privacy of participants' data during comparison. Our protocol enables two parties to compare their private information without revealing any additional details beyond the result of the comparison itself. The main contributions of our paper are as follows. (1) The use of single photons as quantum resources, combined with Z-basis measurement technology, simplifies implementation and enhances the practicality of our approach compared to existing protocols that rely on more complex multi-qubit states and entanglement measurements. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Protocol** & **Quantum States Used** & \begin{tabular}{c} **Quantum** \\ **Measurements** \\ \end{tabular} & \begin{tabular}{c} **The Need for** \\ **Entanglement** \\ **Swapping** \\ \end{tabular} & \begin{tabular}{c} **The Need for** \\ **Unitary Operations** \\ \end{tabular} & \
\begin{tabular}{c} **Quantum** \\ **Communication** \\ \end{tabular} &
\begin{tabular}{c} **Qubit** \\ **Efficiency** \\ \end{tabular} \\ \hline Ref. [19] & Bell states & Bell basis & No & Yes & Two-way & 25\% \\ \hline Ref. [20] & GHZ states & X basis & No & Yes & One-way & 33\% \\ \hline Ref. [21] & x-type states & Bell basis and Z basis & No & Yes & One-way & 25\% \\ \hline Ref. [22] & Five-qubit entangled states & Bell basis and Z basis & No & No & One-way & 40\% \\ \hline Ref. [23] & Six-qubit entangled states & Bell basis & No & No & One-way & 33\% \\ \hline Ref. [24] & Seven-qubit entangled states & Bell basis and Z basis & No & No & One-way & 29\% \\ \hline Ref. [25] & Eight-qubit entangled states & Z basis & No & Yes & One-way & 25\% \\ \hline Ref. [26] & Bell states & GHZ basis & Yes & No & One-way & 50\% \\ \hline Ours & Single photons & Z basis & No & Yes & One-way & 50\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison between our protocol and several existing QPC protocols. (2) Simulations conducted on the IBM Quantum Cloud Platform demonstrate the feasibility of our protocol, while security analysis confirms its resilience against both external attacks and insider threats. (3) Compared to existing QPC protocols that rely on multi-qubit states or \(d\)-dimensional states, our approach exhibits superior efficiency and practicality. The proposed protocol employs single photons and Z-basis measurements as foundational elements, which are more practical than QPC protocols based on multiple-qubit or \(d\)-dimensional quantum states due to the ease of the manipulation and preparation of single photons. (4) Our protocol achieves a qubit efficiency of 50% by using two single photons to compare one bit of classical information, surpassing many existing QPC protocols. Although the proposed protocol can achieve the functionality of equality comparison, it does not consider the impact of a noisy quantum channel. It can only determine whether the private inputs are equal or not, rather than the size relationship between the private inputs. In our upcoming research, we will prioritize the development of the QPC protocol specifically tailored for operation in noisy quantum channels. This focus is essential because, in practical quantum communication scenarios, noise and interference are inevitable, which can adversely affect the fidelity of quantum states and the accuracy of computations. Additionally, we will investigate the functionality of the QPC protocol to facilitate size comparison. Conceptualization, M.H. ; methodology, M.H. ; writing--original draft, M.H. ; writing--review and editing, Y.W. ; supervision, M.H. All authors have read and agreed to the published version of the manuscript. This research was funded by the Open Fund of Network and Data Security Key Laboratory of Sichuan Province (Grant No. NDS2024-1) and Gongga Plan for the \"Double World-class Project\". Not applicable. Data Availability Statement: Data are contained within the article.