Analysis of Quantum Multi-Prover Zero-Knowledge Systems: Elimination of the Honest Condition and Computational Zero-Knowledge Systems for QMIP*

TL;DR

This paper advances quantum multi-prover zero-knowledge systems by removing the honest verifier condition and establishing the existence of computational zero-knowledge protocols under certain conjectures, using GHZ states and local Hamiltonian techniques.

Contribution

It shows that honest-zero-knowledge QMIP* systems can be transformed into general zero-knowledge systems without assumptions and introduces computational zero-knowledge protocols based on a conjecture.

Findings

Honest-zero-knowledge QMIP* systems can be converted to general zero-knowledge systems.

Existence of computational quantum zero-knowledge systems under a natural conjecture.

Introduction of GHZ test and Local Hamiltonian based Interactive protocol as key tools.

Abstract

Zero-knowledge and multi-prover systems are both central notions in classical and quantum complexity theory. There is, however, little research in quantum multi-prover zero-knowledge systems. This paper studies complexity-theoretical aspects of the quantum multi-prover zero-knowledge systems. This paper has two results: 1.QMIP* systems with honest zero-knowledge can be converted into general zero-knowledge systems without any assumptions. 2.QMIP* has computational quantum zero-knowledge systems if a natural computational conjecture holds. One of the main tools is a test (called the GHZ test) that uses GHZ states shared by the provers, which prevents the verifier's attack in the above two results. Another main tool is what we call the Local Hamiltonian based Interactive protocol (LHI protocol). The LHI protocol makes previous research for Local Hamiltonians applicable to check the history state of interactive proofs, and we then apply Broadbent et al.'s zero-knowledge protocol for QMA \cite{BJSW} to quantum multi-prover systems in order to obtain the second result.