Quantum Private Information Retrieval with Sublinear Communication Complexity

TL;DR

This paper introduces a quantum private information retrieval protocol that significantly reduces communication complexity to sublinear levels compared to classical methods, using only O(√n) qubits for large databases.

Contribution

It presents the first quantum protocol achieving sublinear communication complexity for single-server private information retrieval with information-theoretic privacy.

Findings

Quantum protocol reduces communication to O(√n) qubits.

Classical protocols require at least Ω(n) bits.

Quantum approach offers exponential improvement over classical methods.

Abstract

This note presents a quantum protocol for private information retrieval, in the single-server case and with information-theoretical privacy, that has O(\sqrt{n})-qubit communication complexity, where n denotes the size of the database. In comparison, it is known that any classical protocol must use \Omega(n) bits of communication in this setting.