发表机构
Indian Institute of Science（印度科学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究提出并实验实现了一种基于双光子六量子比特纠缠态奇偶结构的非对称密钥生成方案，为传统公钥密码系统提供了物理替代方案，密钥具有内在随机性且安全性基于量子特性。
AI 中文摘要
我们提出并实验演示了一种非对称密钥生成方案，其中公钥和私钥源自六光子纠缠态。该六量子比特纠缠态由两个光子生成，每个光子携带一个偏振量子比特和两个路径量子比特；该态制备为六十四种六量子比特基态中的八种的等叠加态，其中每个光子的三个量子比特构成经典[3,2,2]偶校验码的一个码字，并分发给通信双方爱丽丝（Alice）和鲍勃（Bob）。这确保每个三量子比特组是均匀随机的码字，且两个码字通过关联锁定在一起。奇偶校验约束是一个局域稳定子，因此每一方每轮都可在自身数据上验证该约束，并消除由器件缺陷、探测器暗计数及多光子占据产生的比特翻转错误，之后才将其纳入原始密钥。从任意一个路径量子比特中随机选取的一个公开宣布的比特，可让每一方在不向第三方泄露任何信息的情况下重构另一方的完整三量子比特组。我们采用基于Sagnac结构的II型自发参量下转换（SPDC）源实现了所需的六量子比特态，通过对偏振和路径自由度实施门操作，测得贝尔-CHSH参数S=2.798±0.008。该方案为基于计算困难性假设构建的公钥密码系统提供了一种基于物理的替代方案；多轮生成的用于加密的t比特串将具有内在随机性，若无私钥，需在t量子比特系统上至少运行O(2^t)次才能找到匹配比特以完成解密。
英文摘要
We propose and experimentally demonstrate an asymmetric key-generation scheme in which public and private keys are derived from a six-qubit photonic entangled state. A six-qubit entangled state is generated from two photons, each carrying one polarization and two path qubits. The state is prepared in an equal superposition of eight of the sixty-four six-qubit basis states, in which each photon's three qubits form a codeword of the classical [3,2,2] even-parity code, and are distributed between the two parties, Alice and Bob. This ensures, each triple is a uniformly random codeword and the two codewords are locked together through the correlation. The parity constraint is a local stabilizer, so each party verifies it on its own data every round, and eliminates the bit flip errors arising from imperfections, detector dark counts and multiple occupancy before it enters the raw key. A single publicly announced bit, chosen at random from either of the path qubits, allows each party to reconstruct the other's full triple while leaking no information to third party. We realize the desired six-qubit state using a Sagnac-based type-II SPDC source, reporting a Bell-CHSH parameter S = 2.798 +/- 0.008, by implementing gate operation on polarization and path degree's of freedom. This approach provides a physics-based alternative to public-key cryptosystems built on computational hardness assumptions. A t-bit string generated from multiple rounds for encryption will be intrinsically random. Without the private key, one needs at least O(2^t) runs on an t-qubit quantum system to find the matching bit to decrypt.
Comments12 pages, 8 figures
