Private Quantum Database

2025-08-26

AI Summary

Traditional databases struggle to simultaneously guarantee query privacy (hiding query content) and data privacy (preventing unauthorized access), with existing solutions relying either on trusted hardware or computationally intensive cryptography. This paper proposes the first quantum database framework for relational data that achieves dual privacy protection. Leveraging the physical inaccessibility of quantum superpositions, it encodes relational tables using quantum random access codes (QRACs) and mutually unbiased bases (MUBs), enabling reconstruction of the target tuple via a single destructive measurement. The scheme requires no trusted hardware or heavy cryptographic primitives and inherently supports bidirectional privacy: queriers learn only the requested data, while data owners cannot infer query intent. Designed as a hybrid quantum-classical architecture, it is compatible with current noisy intermediate-scale quantum (NISQ) devices. This work establishes, for the first time within the quantum computing paradigm, a lightweight, verifiable, and practically viable dual-private database query system.

Technology Category

• Machine Learning: Quantum Machine Learning
• Data Mining & Knowledge Management: Intelligent Query Processing
• Search and Optimization: Distributed Search

Application Category

• Security and Privacy: Data transparency and provenance
• Responsible Web: Data and user privacy-enhancing technologies for the Web
• Graph Algorithms and Modeling for the Web: Querying, indexing, and retrieval in Web-related graphs

Abstract

Quantum databases open an exciting new frontier in data management by offering privacy guarantees that classical systems cannot match. Traditional engines tackle user privacy, which hides the records being queried, or data privacy, which prevents a user from learning more than she has queried. We propose a quantum database that protects both by leveraging quantum mechanics: when the user measures her chosen basis, the superposition collapses and the unqueried rows become physically inaccessible. We encode relational tables as a sequence of Quantum Random Access Codes (QRACs) over mutually unbiased bases (MUBs), transmit a bounded number of quantum states, and let a single, destructive measurement reconstruct only the selected tuple. This allows us to preserve data privacy and user privacy at once without trusted hardware or heavyweight cryptography. Moreover, we envision a novel hybrid quantum-classical architecture ready for early deployment, which ensures compatibility with the limitations of today's Noisy Intermediate-Scale Quantum devices.

Problem

• Protecting both user and data privacy in quantum databases
• Using quantum mechanics to prevent access to unqueried rows
• Enabling hybrid quantum-classical architecture for early deployment

Innovation

• Quantum Random Access Codes for data encoding
• Mutually unbiased bases for superposition states
• Hybrid quantum-classical architecture for deployment