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A Quantum Walk-Enabled Blockchain with Weighted Quantum Voting Consensus

Chong-Qiang Ye, Heng-Ji Li, Jian Li, Xiao-Yu Chen

TL;DR

This work addresses the fragility and scalability of entanglement-dependent quantum blockchains by introducing a quantum-walk based framework that links blocks through walk evolution rather than long-range entanglement. It couples this structure with a weighted quantum voting-based delegated proof-of-stake (QDPoS) consensus, enabling weight-aware representation and secure block validation. Circuit-level simulations demonstrate correctness of the weighted voting and inherent tamper-detection in block construction, suggesting improved practicality for quantum-era ledgers. The approach offers a scalable, quantum-native alternative with strong security guarantees suitable for resisting quantum adversaries while maintaining verifiability and fairness.

Abstract

Quantum blockchains provide inherent resilience against quantum adversaries and represent a promising alternative to classical blockchain systems in the quantum era. However, existing quantum blockchain architectures largely depend on entanglement to maintain inter-block connections, facing challenges in stability, consensus efficiency, and system verification. To address these issues, this work proposes a novel quantum blockchain framework based on quantum walks, which reduces reliance on entanglement while improving stability and connection efficiency. We further propose a quantum consensus mechanism based on a weighted quantum voting protocol, which enables a fairer voting process while reflecting the weights of different nodes. To validate the proposed framework, we conduct circuit simulations to evaluate the correctness and effectiveness of both the quantum walk-based block construction and the quantum voting consensus mechanism. Compared with existing entanglement-dependent approaches, our framework achieves stronger stability and enables simpler verification of block integrity, making it a practical candidate for quantum-era blockchain applications.

A Quantum Walk-Enabled Blockchain with Weighted Quantum Voting Consensus

TL;DR

This work addresses the fragility and scalability of entanglement-dependent quantum blockchains by introducing a quantum-walk based framework that links blocks through walk evolution rather than long-range entanglement. It couples this structure with a weighted quantum voting-based delegated proof-of-stake (QDPoS) consensus, enabling weight-aware representation and secure block validation. Circuit-level simulations demonstrate correctness of the weighted voting and inherent tamper-detection in block construction, suggesting improved practicality for quantum-era ledgers. The approach offers a scalable, quantum-native alternative with strong security guarantees suitable for resisting quantum adversaries while maintaining verifiability and fairness.

Abstract

Quantum blockchains provide inherent resilience against quantum adversaries and represent a promising alternative to classical blockchain systems in the quantum era. However, existing quantum blockchain architectures largely depend on entanglement to maintain inter-block connections, facing challenges in stability, consensus efficiency, and system verification. To address these issues, this work proposes a novel quantum blockchain framework based on quantum walks, which reduces reliance on entanglement while improving stability and connection efficiency. We further propose a quantum consensus mechanism based on a weighted quantum voting protocol, which enables a fairer voting process while reflecting the weights of different nodes. To validate the proposed framework, we conduct circuit simulations to evaluate the correctness and effectiveness of both the quantum walk-based block construction and the quantum voting consensus mechanism. Compared with existing entanglement-dependent approaches, our framework achieves stronger stability and enables simpler verification of block integrity, making it a practical candidate for quantum-era blockchain applications.

Paper Structure

This paper contains 38 sections, 3 theorems, 30 equations, 10 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Related work
  3. Quantum blockchains
  4. Quantum Foundations for Blockchain Systems
  5. Quantum Consensus Mechanisms
  6. Quantum walks
  7. Two-direction discrete quantum walks on a circle
  8. Quantum hash function based on quantum walks
  9. Quantum Blockchain Construction via Quantum Walks
  10. Quantum block structure construction
  11. Initialization of position states
  12. Mapping of block information
  13. Data embedding via quantum walk evolution
  14. Computation of block hash
  15. Quantum consensus mechanism
  16. ...and 23 more sections

Key Result

Theorem 1

Let node $N_i$ use a quantum signature scheme. For any QPT adversary $\mathcal{A}$, the probability that $\mathcal{A}$ produces a fraudulent tuple $(M', qs_i(M'))$ that passes verification under public key $pk_i$ is negligible in the security parameter $\kappa$.

Figures (10)

  • Figure 1: Schematic of a quantum blockchain, showing quantum blocks encoding classical data via phase angles and linked through entangled states.
  • Figure 2: Circuit diagram of quantum walk evolution operation.
  • Figure 3: Schematic diagram of chain-structured state evolution based on quantum walk.
  • Figure 4: Schematic of the quantum block structure based on quantum walks. Each block corresponds to a quantum state $|\phi\rangle$, composed of $n$ quantum walk states $\lvert\psi_1\rangle, \lvert\psi_2\rangle, \dots, \lvert\psi_n\rangle$. The initial positions of these walks are derived from the hash of the preceding block, while the number of walk steps encodes the information of the current block.
  • Figure 5: Workflow of the proposed quantum blockchain.
  • ...and 5 more figures

Theorems & Definitions (9)

  • Definition 1
  • Theorem 1
  • proof
  • Definition 2
  • Theorem 2
  • proof
  • Definition 3
  • Theorem 3
  • proof