In the era of extensive data growth, robust and efficient mechanisms are needed to store and manage vast amounts of digital information, such as Data Storage Systems (DSSs). Concurrently, privacy concerns have arisen, leading to the development of techniques like Private Information Retrieval (PIR) to enable data access while preserving privacy. A PIR protocol allows users to retrieve information from a database without revealing the specifics of their query or the data they are accessing. With the advent of quantum computing, researchers have explored the potential of using quantum systems to enhance privacy in information retrieval. In a Quantum Private Information Retrieval (QPIR) protocol, a user can retrieve information from a database by downloading quantum systems from multiple servers, while ensuring that the servers remain oblivious to the specific information being accessed. This scenario offers a unique advantage by leveraging the inherent properties of quantum systems to provide enhanced privacy guarantees and improved communication rates compared to classical PIR protocols. In this thesis we consider the QPIR setting where the queries and the coded storage systems are classical, while the responses from the servers are quantum. This problem was treated by Song et al. for replicated storage and different collusion patterns. This thesis aims to develop QPIR protocols for coded storage by combining known classical PIR protocols with quantum communication algorithms, achieving enhanced privacy and communication costs. We consider different storage codes and robustness assumptions, and we prove that the achieved communication cost is always lower than the classical counterparts.

翻译：在大数据时代，需要强大且高效的机制来存储和管理海量数字信息，例如数据存储系统。与此同时，隐私问题也随之凸显，促使了诸如私有信息检索（PIR）等技术的发展，以便在访问数据时保护隐私。PIR协议允许用户在不泄露其查询细节或所访问数据的情况下从数据库中检索信息。随着量子计算的出现，研究人员开始探索利用量子系统增强信息检索中隐私保护的潜力。在量子私有信息检索协议中，用户通过从多个服务器下载量子系统来从数据库中检索信息，同时确保服务器对所访问的具体信息保持无知。与经典PIR协议相比，该场景利用量子系统的固有特性提供了更强的隐私保证和更优的通信速率，具有独特优势。本文考虑一种量子私有信息检索设定，其中查询和编码存储系统是经典的，而来自服务器的响应是量子的。Song等人先前针对复制存储和不同合谋模式处理了该问题。本文旨在通过将已知经典PIR协议与量子通信算法相结合，为编码存储系统开发量子私有信息检索协议，以实现更强的隐私保护和更低的通信成本。我们考虑了不同的存储编码和鲁棒性假设，并证明所实现的通信成本始终低于经典方案。