We propose a scalable quantum architectures which can improve operation of Blockchain systems. We focus on permissioned blockchains with consensus derived from Practical Byzantine Fault Tolerance (PBFT). We propose multipartite entanglement quantum architectures that can perform PBFT. Further we develop quantum systems and algorithms that can support Proof of Stake (PoS) voting as well as voter election and voting in delegated Proof of Stake systems. Validating nodes within a cluster hold qubits entangled in multipartite structure. Due to maximally connected entanglement they jointly perform voting and calculate voting results. We propose algorithms that can track voter's behavior and detect collusion and voting centralization problem.
We propose a scalable quantum architectures which can improve operation of Blockchain systems. We focus on permissioned blockchains with consensus derived from Practical Byzantine Fault Tolerance (PBFT). We propose multipartite entanglement quantum architectures that can perform PBFT. Further we develop quantum systems and algorithms that can support Proof of Stake (PoS) voting as well as voter election and voting in delegated Proof of Stake systems. Validating nodes within a cluster hold qubits entangled in multipartite structure. Due to maximally connected entanglement they jointly perform voting and calculate voting results. We propose algorithms that can track voter's behavior and detect collusion and voting centralization problem.
In this paper, we propose a novel consensus mechanism utilizing the quantum properties of qubits. This move from classical computing to quantum computing is shown to theoretically enhance the scalability and speed of distributed consensus as well as improve security and be a potential solution for the problem of blockchain interoperability. Using this method may circumvent the common problem known as the Blockchain Trilemma, enhancing scalability and speed without sacrificing de-centralization or byzantine fault tolerance [1]. Consensus speed and scalability is shown by removing the need for multicast responses and exploiting quantum properties to ensure that only a single multicast is required. We also leverage work done on the E91 quantum key distribution protocol [2] to securely transmit values and prevent a man-in-the-middle attack or system disturbance, enhancing confidentiality and integrity of transmitted information. Distributed ledger interoperability is explored by proposing a system to achieve a verifiable bridge for private transactions between a small private network and its corresponding consortium network. A proof-of-concept using IBM’s Qskit is shown from which initial results appear to show a strong sensitivity to non-consensus which could be useful in many applications. The present practical feasibility of the above is shown and future work is explored.
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.
This study proposes an experimental model of blockchain consensus that integrates the quantum computing paradigm with classical digital signature mechanisms. In the model, validators employ a commit–reveal scheme using ECDSA or RSA digital signatures, and the decision-making process is modeled in the presence of Byzantine-behaving nodes. The final consensus decision is based on a quantum voting primitive implemented using a GHZ-type entangled state through the Qiskit simulator. In addition, a per-qubit calibration and probability mitigation method is applied to reduce measurement errors. The research results are visualized through the quantum confirmation share per block, the distribution of votes from honest and Byzantine validators, and histograms of raw and mitigated probabilities. The obtained results allow the evaluation of the stability of quantum-based consensus mechanisms and their resilience to Byzantine faults.
Popularized by the Bitcoin cryptocurrency, blockchain technology establishes a decentralized digital framework that utilizes cryptographic and consensus protocols to secure data against unauthorized modification. Consequently, blockchain has found broad adoption across diverse fields, including finance, data management, healthcare, and digital asset governance. In the quantum computing era, a paramount objective for blockchain is to preserve its foundational advantages of cryptographic integrity and decentralized fault-tolerant resilience. In principle, quantum digital signatures and quantum Byzantine agreement protocols offer foundational security guarantees and tolerate up to one-half of malicious nodes for blockchain. However, the practical realization of such a quantum-enhanced blockchain remains a significant and multifaceted challenge. Here, we propose and experimentally demonstrate a fully operational hybrid quantum blockchain architecture built on photonic integrated circuits and deployed over commercially available classical telecommunications infrastructure. The system achieves a fault tolerance of nearly one-half, surpassing the classical limit, while reaching consensus on a timescale of seconds. A deployed food traceability application validates the practicality of the proposed architecture, achieving a throughput of approximately 500 transactions per second. This work establishes a foundation for practical quantum blockchains, enabling secure, scalable, and decentralized information processing in the emerging quantum era.
Quantum blockchain is expected to offer an alternative to classical blockchain to resist malicious attacks laughed by future quantum computers. Although a few quantum blockchain schemes have been constructed, their efficiency is low and unable to meet application requirements due to the fact that they lack of a suitable consensus mechanism. To tackle this issue, a consensus mechanism called quantum delegated proof of stake (QDPoS) is constructed by using quantum voting to provide fast decentralization for the quantum blockchain scheme at first. Then an efficient scheme is proposed for quantum blockchain based on QDPoS, where the classical information is initialized as a part of each single quantum state and these quantum states are entangled to form the chain. Compared with previous methods, the designed quantum blockchain scheme is more complete and carried out with higher efficiency, which greatly contributes to better adapting to the challenges of the quantum era.
In the age of digital transformation, the integrity and security of online voting systems have become a growing concern. Traditional cryptography methods are vulnerable to advances in quantum computing, demanding the need for more secure alternatives. This paper explores the application of quantum cryptography in enhancing the security of blockchain-based voting systems, a decentralized and transparent approach to conduct elections. We introduce a novel quantum-resistant voting protocol that integrates Quantum Key Distribution (QKD) with post-quantum cryptographic algorithms, ensuring secure voter authentication, vote casting, and tallying. The methodology combines quantum encryption with blockchain's immutability to create a tamper-proof voting ledger, preventing unauthorized access and vote manipulation. It gives an analysis of potential real-world implementations, positioning a hybrid quantum-blockchain framework as a promising solution for future secure electronic voting systems.