ABSTRACT Objective With the rapid advancement of quantum computing technologies, Quantum Federated Learning (QFL) has emerged as a promising framework for privacy‐preserving quantum machine learning (QML). QFL provides a promising approach for privacy‐preserving quantum machine learning by enabling collaborative model training without sharing raw data. However, malicious or unreliable quantum clients may submit poisoned or low‐quality models, threatening the reliability of global aggregation. This study aims to develop a secure and robust QFL framework against such adversarial behaviors. Methods We propose a novel Quantum Federated Lasso (QFLasso) framework built on a quantum blockchain infrastructure. Local quantum models are trained with Lasso regularization to achieve sparse representations, and model updates are recorded on the blockchain. Quantum validators verify the quality and integrity of submitted models before aggregation. An anonymous quantum consensus mechanism is further introduced to ensure reliable agreement while preserving validator anonymity. Result The proposed framework integrates quantum Lasso optimization, federated learning, blockchain‐based verification, and anonymous quantum consensus to enhance the security, robustness, and privacy preservation of distributed quantum learning systems. The validator verification mechanism effectively filters unreliable model updates, while the anonymous consensus protocol improves resistance against dishonest or colluding validators and prevents targeted attacks on individual participants. Conclusion QFLasso provides a secure and scalable architecture for privacy‐preserving quantum intelligence, offering potential applications in secure quantum finance, distributed quantum sensing, and collaborative quantum medical diagnosis.
ABSTRACT Objective With the rapid advancement of quantum computing technologies, Quantum Federated Learning (QFL) has emerged as a promising framework for privacy‐preserving quantum machine learning (QML). QFL provides a promising approach for privacy‐preserving quantum machine learning by enabling collaborative model training without sharing raw data. However, malicious or unreliable quantum clients may submit poisoned or low‐quality models, threatening the reliability of global aggregation. This study aims to develop a secure and robust QFL framework against such adversarial behaviors. Methods We propose a novel Quantum Federated Lasso (QFLasso) framework built on a quantum blockchain infrastructure. Local quantum models are trained with Lasso regularization to achieve sparse representations, and model updates are recorded on the blockchain. Quantum validators verify the quality and integrity of submitted models before aggregation. An anonymous quantum consensus mechanism is further introduced to ensure reliable agreement while preserving validator anonymity. Result The proposed framework integrates quantum Lasso optimization, federated learning, blockchain‐based verification, and anonymous quantum consensus to enhance the security, robustness, and privacy preservation of distributed quantum learning systems. The validator verification mechanism effectively filters unreliable model updates, while the anonymous consensus protocol improves resistance against dishonest or colluding validators and prevents targeted attacks on individual participants. Conclusion QFLasso provides a secure and scalable architecture for privacy‐preserving quantum intelligence, offering potential applications in secure quantum finance, distributed quantum sensing, and collaborative quantum medical diagnosis.
Quantum federated learning (QFL) is emerging as a key enabler for intelligent, secure, and privacy-preserving model training in next-generation 6G networks. By leveraging the computational advantages of quantum devices, QFL offers significant improvements in learning efficiency and resilience against quantum-era threats. However, future 6G environments are expected to be highly dynamic, decentralized, and data-intensive, which necessitates moving beyond traditional centralized federated learning frameworks. To meet this demand, blockchain technology provides a decentralized, tamper-resistant infrastructure capable of enabling trustless collaboration among distributed quantum edge devices. This paper presentsQFLchain, a novel framework that integrates QFL with blockchain to support scalable and secure 6G intelligence. In this work, we investigate four key pillars ofQFLchainin the 6G context: 1) communication and consensus overhead; 2) scalability and storage overhead; 3) energy inefficiency; and 4) security vulnerability. A case study is also presented, demonstrating potential advantages ofQFLchain, based on simulation, over state-of-the-art approaches in terms of training performance.
Federated learning enables decentralized, privacy-preserving training but remains vulnerable to privacy leakage in the quantum era. Quantum federated learning (QFL) offers a promising path toward enhanced security and efficiency. However, a practical and experimentally validated QFL protocol utilizing near-term quantum techniques to address data privacy has been lacking. Here, we present QuNetQFL, a QFL protocol implemented on quantum networks, in which local model updates are masked with distributed quantum secret keys, offering information-theoretic security during aggregation. We experimentally validate the protocol on a 4-client quantum network and benchmark its performance using the generated keys on quantum and real-world datasets. Adding a single quantum client substantially improves global accuracy for classifying multipartite entangled and nonstabilizer quantum datasets. For language tasks, we apply QuNetQFL to sentiment analysis by federated fine-tuning of a hybrid classical-quantum language model, achieving comparable and robust performance in simulation and on real quantum hardware. Large-scale simulations further demonstrate scalability to 200 clients for handwritten-digit recognition, with rapid convergence and a 75% reduction in communication cost via model compression. Our work establishes a practical and scalable route to quantum-secure federated learning for the emerging quantum internet.
Quantum federated learning (QFL) enables collaborative training of quantum machine learning (QML) models across distributed quantum devices without raw data exchange. However, QFL remains vulnerable to adversarial attacks, where shared QML model updates can be exploited to undermine information privacy. In the context of noisy intermediate-scale quantum (NISQ) devices, a key question arises: How can inherent quantum noise be leveraged to enforce differential privacy (DP) and protect model information during training and communication? This paper explores a novel DP mechanism that harnesses quantum noise to safeguard quantum models throughout the QFL process. By tuning noise variance through measurement shots and depolarizing channel strength, our approach achieves desired DP levels tailored to NISQ constraints. Simulations demonstrate the framework's effectiveness by examining the relationship between differential privacy budget and noise parameters, as well as the trade-off between security and training accuracy. Additionally, we demonstrate the framework's robustness against an adversarial attack designed to compromise model performance using adversarial examples, with evaluations based on critical metrics such as accuracy on adversarial examples, confidence scores for correct predictions, and attack success rates. The results reveal a tunable trade-off between privacy and robustness, providing an efficient solution for secure QFL on NISQ devices with significant potential for reliable quantum computing applications.
The mix of quantum computing and machine learning has introduced strong quantum models able to resolve challenging tasks efficiently. Still, the use of centralized QML systems could present challenges with privacy because sharing quantum data with untrusted aggregators is especially risky. This study describes a method called Privacy-Preserving Quantum Federated Learning (PQFL), which allows multiple clients to jointly train quantum models while maintaining data confidentiality. This system offers security by combining QHE and QDP to cover the processes of aggregating protected models and enforcing privacy on the data. Hybrid quantum-classical studies reveal that PQFL is both accurate and advanced in protecting privacy and communication security. According to these results, PQFL works effectively in privacy-friendly domains including healthcare, genomics, and finance, where data needs to be managed securely.
In recent years, the growing demand for secure, efficient, and scalable machine learning has highlighted significant challenges in traditional Federated Learning (FL) systems. These challenges include computational inefficiencies in handling large-scale, high-dimensional data, privacy concerns, and the limitations of classical hardware in solving complex optimization problems. Additionally, the increasing complexity of data and the need for more robust privacy-preserving methods have pushed the boundaries of classical FL. To address these issues, this paper presents a detailed framework for Quantum Federated Learning (QFL), where quantum computing and FL converge to enable distributed quantum model training with enhanced privacy preservation. The system is modeled using local quantum models on clients and a global aggregation strategy at the server. We develop quantum gradient-based optimization with quantum cross-entropy loss, privacy preservation through encryption, and robustness to quantum noise. A set of theorems is provided to prove the correctness and efficiency of the model, supported by rigorous mathematical formulations. We used IBM Qiskit for the simulation and compared our proposed QFL with classical FL. The results demonstrate that our QFL outperformed classical FL in terms of accuracy, precision, recall, and F1 score.
Recent advancements in Quantum Neural Networks (QNNs) have demonstrated theoretical and experimental performance superior to their classical counterparts in a wide range of applications. However, existing centralized QNNs cannot solve many real-world problems because collecting large amounts of training data to a common public site is time-consuming and, more importantly, violates data privacy. Federated Learning (FL) is an emerging distributed machine learning framework that allows collaborative model training on decentralized data residing on multiple devices without breaching data privacy. Some initial attempts at Quantum Federated Learning (QFL) either only focus on improving the QFL performance or rely on a trusted quantum server that fails to preserve data privacy. In this work, we propose CryptoQFL, a QFL framework that allows distributed QNN training on encrypted data. CryptoQFL is (1) secure, because it allows each edge to train a QNN with local private data, and encrypt its updates using quantum homomorphic encryption before sending them to the central quantum server; (2) communication-efficient, as CryptoQFL quantize local gradient updates to ternary values, and only communicate non-zero values to the server for aggregation; and (3) computation-efficient, as CryptoQFL presents an efficient quantum aggregation circuit with significantly reduced latency compared to state-of-the-art approaches.