This article presents enhanced dynamical distributing quantum compilation (EDDQC), an optimized method for distributed quantum computing (DQC) using linear nearest neighbor (LNN) architecture integrated with quantum switches. By leveraging the symmetry of LNN topology and designating dangling qubits as communication links, our approach optimizes compilation for high local connectivity, sparse full connectivity algorithms (HLC-SFC) like quantum approximate optimization algorithm (QAOA) and quantum Fourier transform (QFT). Experimental results demonstrate significant performance improvements over traditional methods, including reductions in cross-group swaps by up to 67.2%, gate count by 43.8%, and total execution cycles by up to 40%. We also utilize the area law of entanglement entropy to limit entanglement growth in our 1-D system. Our comprehensive approach combines LNN chains’ efficiency with reconfigurable network flexibility, enhancing scalability and robustness for large-scale quantum computations.

Reinforcement learning (RL) using conventional neural networks (NN) has significantly progressed in various applications. However, conventional RL needs help training in environments with large-scale action dimensions, such as coordinated mobility/satellite systems. Quantum reinforcement learning (QRL) with quantum NN (QNN) can address this problem through superposition and entanglement, one of the great features of quantum mechanics. Based on its ‘i) fast convergence’ and ‘ii) high scalability’, unique advantages of QRL that distinguish it from conventional RL, this paper highlights the potential for QRL utilization in coordinated mobility and satellite systems.

Blockchain transaction data exhibits high dimensionality, noise, and intricate feature entanglement, presenting significant challenges for traditional clustering algorithms. In this study, we conduct a comparative analysis of three clustering approaches: (1) Classical K-Means Clustering, applied to pre-processed feature representations; (2) Hybrid Clustering, wherein classical features are enhanced with quantum random features extracted using randomly initialized quantum neural networks (QNNs); and (3) Fully Quantum Clustering, where a QNN is trained in a self-supervised manner leveraging a SwAV-based loss function to optimize the feature space for clustering directly. The proposed experimental framework systematically investigates the impact of quantum circuit depth and the number of learned prototypes, demonstrating that even shallow quantum circuits can effectively extract meaningful non-linear representations, significantly improving clustering performance.

Critical infrastructures (CI)-including power grids, financial systems, communication networks, and transportation networks-are essential to societal stability and economic security. As these systems grow increasingly complex and interconnected, they face mounting challenges in scalability, robustness, real-time decision-making, and data privacy. While classical artificial intelligence (AI) and machine learning (ML) techniques have been applied to enhance CI monitoring, optimization, and control, they are often constrained by data heterogeneity, centralized architectures, and limited adaptability. Quantum computing (QC), known for its potential to solve certain computational problems exponentially faster than classical methods, has opened new possibilities in this domain. Quantum artificial intelligence (QAI), which combines quantum computing with AI techniques, offers transformative opportunities, particularly through paradigms such as federated quantum machine learning (FedQML) and quantum reinforcement learning (QRL). These approaches promise privacy-preserving distributed intelligence and dynamic control across CI systems. In this article, we survey recent developments in QAI and explore their applications in critical infrastructure domains. We also highlight key challenges and outline a forward-looking roadmap toward resilient, secure, and quantum-enhanced infrastructure systems.

This paper investigates the potential of quantum-enhanced models for time series forecasting in environments where time is a fundamental constraint. The focus is on on the quantum long short term memory networks with reservoir (QR-LSTM), and our proposed novel extension, the Autoencoded Quantum Reservoir LSTM Model (QR-LSTM-AE). The QR-LSTM, while offering substantial computational benefits in terms of time and resource efficiency, incurs a slight decrease in performance relative to the fully trainable quantum LSTM model. To address this trade-off, we introduce the QR-LSTM-AE, which utilizes an autoencoder-based strategy to recover performance lost in the reservoir alone, achieving superior accuracy without the need for full retraining. This approach not only maintains the efficiency of the QR-LSTM but also significantly reduces the computational cost associated with adapting to new data or time series, making it ideal for real-time forecasting applications. The experiments are carried out on a energy-related, highly volatile dataset, and results underscore the importance of balancing predictive accuracy with computational efficiency, highlighting the potential of quantum models to offer practical solutions in time-constrained environments. Our findings demonstrate that the QR-LSTM-AE effectively balances predictive accuracy and computational efficiency, paving the way for future advancements in quantum-enhanced forecasting through self-adaptive models, quantum autoencoders, and attention-based reservoir computing.

Quantum Machine Learning (QML) is rapidly emerging as a frontier field, combining quantum computing and artificial intelligence to address fundamental challenges in learning scalability and adaptability. This paper explores how the principles of quantum mechanics can be harnessed-particularly through variational quantum circuits (VQCs)-to design efficient QML architectures suitable for noisy intermediate-scale quantum (NISQ) devices. We present recent advancements including Quantum Federated Learning (QFL) for privacy-preserving distributed intelligence, Quantum Long Short-Term Memory (QL-STM) networks for sequential pattern modeling, and Quantum Reinforcement Learning (QRL) for dynamic decision-making. Furthermore, we introduce the Quantum Fast Weight Programmer (QFWP), a mechanism for rapid, context-driven parameter adaptation to support meta-learning in quantum systems. We also discuss differentiable quantum architecture search (DiffQAS) as a means of automatically optimizing quantum circuit structures. Despite limitations in quantum hardware-such as decoherence, noise, and limited qubit counts-we review mitigation strategies including hybrid quantum-classical training, error-aware optimization, and scalable architectural design. This work outlines a forward-looking framework for building scalable, adaptive, and trustworthy Quantum AI systems.

Quantum machine learning (QML) is a rapidly growing field that combines quantum computing principles with traditional machine learning. It seeks to revolutionize machine learning by harnessing the unique capabilities of quantum mechanics and employs machine learning techniques to advance quantum computing research. This paper presents an overview of quantum computing for the machine learning paradigm, where variational quantum circuits (VQC) are used to develop QML architectures on noisy intermediate-scale quantum (NISQ) devices. We discuss machine learning for the quantum computing paradigm, showcasing our recent theoretical and empirical findings. In particular, we delve into future directions for studying QML, exploring the potential industrial impacts of QML research.

Recent advancements in quantum computing (QC) and machine learning (ML) have fueled significant research efforts aimed at integrating these two transformative technologies. Quantum machine learning (QML), an emerging interdisciplinary field, leverages quantum principles to enhance the performance of ML algorithms. Concurrently, the exploration of systematic and automated approaches for designing high-performance quantum circuit architectures for QML tasks has gained prominence, as these methods empower researchers outside the quantum computing domain to effectively utilize quantum-enhanced tools. This tutorial will provide an in-depth overview of recent breakthroughs in both areas, highlighting their potential to expand the application landscape of QML across diverse fields.

In this paper, we propose an efficient compilation method for distributed quantum computing (DQC) using the Linear Nearest Neighbor (LNN) architecture. By exploiting the LNN topology’s symmetry, we optimize quantum circuit compilation for High Local Connectivity, Sparse Full Connectivity (HLC-SFC) algorithms like Quantum Approximate Optimization Algorithm (QAOA) and Quantum Fourier Transform (QFT). We also utilize dangling qubits to minimize non-local interactions and reduce SWAP gates. Our approach significantly decreases compilation time, gate count, and circuit depth, improving scalability and robustness for large-scale quantum computations.

In this work, we introduce a Distributed Quantum Long Short-Term Memory (QLSTM) framework that leverages modular quantum computing to address scalability challenges on Noisy Intermediate-Scale Quantum (NISQ) devices. By embedding variational quantum circuits into LSTM cells, the QLSTM captures long-range temporal dependencies, while a distributed architecture partitions the underlying Variational Quantum Circuits (VQCs) into smaller, manageable subcircuits that can be executed on a network of quantum processing units. We assess the proposed framework using nontrivial benchmark problems such as damped harmonic oscillators and Nonlinear Autoregressive Moving Average sequences. Our results demonstrate that the distributed QLSTM achieves stable convergence and improved training dynamics compared to classical approaches. This work underscores the potential of modular, distributed quantum computing architectures for large-scale sequence modeling, providing a foundation for the future integration of hybrid quantum-classical solutions into advanced Quantum High-performance computing (HPC) ecosystems.

Variational quantum Eigensolver (VQE) is a leading candidate for harnessing quantum computers to advance quantum chemistry and materials simulations, yet its training efficiency deteriorates rapidly for large Hamiltonians. Two issues underlie this bottleneck: (i) the no-cloning theorem imposes a linear growth in circuit evaluations with the number of parameters per gradient step; and (ii) deeper circuits encounter barren plateaus (BPs), leading to exponentially increasing measurement overheads. To address these challenges, here we propose a deep learning framework, dubbed Titan, which identifies and freezes inactive parameters of a given ansätze at initialization for a specific class of Hamiltonians, reducing the optimization overhead without sacrificing accuracy. The motivation of Titan starts with our empirical findings that a subset of parameters consistently has negligible influence on training dynamics. Its design combines a theoretically grounded data construction strategy, ensuring each training example is informative and BP-resilient, with an adaptive neural architecture that generalizes across ansätze of varying sizes. Across benchmark transverse-field Ising models, Heisenberg models, and multiple molecule systems up to $30$ qubits, Titan achieves up to $3\times$ faster convergence and $40$–$60\%$ fewer circuit evaluations than state-of-the-art baselines, while matching or surpassing their estimation accuracy. By proactively trimming parameter space, Titan lowers hardware demands and offers a scalable path toward utilizing VQE to advance practical quantum chemistry and materials science.

Federated learning (FL) has emerged as a powerful paradigm for decentralized training, particularly in privacy-sensitive fields such as medical Internet of Things (IoT) services, where data security is important. However, FL faces challenges due to nonindependent and identically distributed (non-IID) data among clients, which can lead to suboptimal performance. In addition, there is a risk of data leakage during the aggregation process. To address these issues, we propose a novel approach using an auction mechanism to filter out unreliable clients, ensuring that only trustworthy participants are involved in the learning process. The selected clients are organized in a ring topology, eliminating the need for a central server and thereby reducing the risk of data breaches. Additionally, we leverage quantum neural networks (QNNs) to enhance security further, utilizing the quantum no-cloning theorem to prevent the duplication of quantum parameters. The results demonstrate that our approach can handle non-IID data distributions effectively and improve model performance, even with small and imbalanced datasets.

This tutorial offers a hands-on introduction into the captivating field of quantum machine learning (QML). Beginning with the bedrock of quantum information science (QIS)-including essential elements like qubits, single and multiple qubit gates, measurements, and entanglement-the session swiftly progresses to foundational QML concepts. Participants will explore parameterized or variational circuits, data encoding or embedding techniques, and quantum circuit design principles. Delving deeper, attendees will examine various QML models, including the quantum support vector machine (QSVM), quantum feed-forward neural network (QNN), and quantum convolutional neural network (QCNN). Pushing boundaries, the tutorial delves into cutting-edge QML models such as quantum recurrent neural networks (QRNN) and quantum reinforcement learning (QRL), alongside privacy-preserving techniques like quantum federated machine learning, bolstered by concrete programming examples. Throughout the tutorial, all topics and concepts are brought to life through practical demonstrations executed on a quantum computer simulator. Designed with novices in mind, the content caters to those eager to embark on their journey into QML. Attendees will also receive guidance on further reading materials, as well as software packages and frameworks to explore beyond the session.

Quantum reinforcement learning (QRL) has emerged as a framework to solve sequential decision-making tasks, showcasing empirical quantum advantages. A notable development is through quantum recurrent neural networks (QRNNs) for memory-intensive tasks such as partially observable environments. However, QRL models incorporating QRNN encounter challenges such as inefficient training of QRL with QRNN, given that the computation of gradients in QRNN is both computationally expensive and time-consuming. This work presents a novel approach to address this challenge by constructing QRL agents utilizing QRNN-based reservoirs, specifically employing quantum long short-term memory (QLSTM). QLSTM parameters are randomly initialized and fixed without training. The model is trained using the asynchronous advantage actor-critic (A3C) algorithm. Through numerical simulations, we validate the efficacy of our QLSTM-Reservoir RL framework. Its performance is assessed on standard benchmarks, demonstrating comparable results to a fully trained QLSTM RL model with identical architecture and training settings.

The preservation of privacy is a critical concern in the implementation of artificial intelligence on sensitive training data. There are several techniques to preserve data privacy but quantum computations are inherently more secure due to the nocloning theorem, resulting in a most desirable computational platform on top of the potential quantum advantages. There have been prior works in protecting data privacy by Quantum Federated Learning (QFL) and Quantum Differential Privacy (QDP) studied independently. However, to the best of our knowledge, no prior work has addressed both QFL and QDP together yet. Here, we propose to combine these privacy-preserving methods and implement them on the quantum platform, so that we can achieve comprehensive protection against data leakage (QFL) and model inversion attacks (QDP). This implementation promises more efficient and secure artificial intelligence. In this paper, we present a successful implementation of these privacy-preservation methods by performing the binary classification of the Cats vs Dogs dataset. Using our quantum-classical machine learning model, we obtained a test accuracy of over 0.98, while maintaining epsilon values less than 1.3. We show that federated differentially private training is a viable privacy preservation method for quantum machine learning on Noisy Intermediate-Scale Quantum (NISQ) devices.

The utility of machine learning has rapidly expanded in the last two decades and presented an ethical challenge. Papernot et. al. developed a technique, known as Private Aggregation of Teacher Ensembles (PATE) to enable federated learning in which multiple distributed teachers are trained on disjoint data sets. This study is the first to apply PATE to an ensemble of quantum neural networks (QNN) to pave a new way of ensuring privacy in quantum machine learning (QML).

Quantum computing offers potential advancements in machine learning. However, the impact of concept drift remains unexplored when introducing data streams into quantum machine learning models. Hence, this study is the first to examine the impact of concept drift on quantum support vector machines and quantum neural networks, contrasting them with their classical counterparts. Our study is based on two data streams provided by the RiverML Library, namely, the real KDDCUP99 dataset and the synthetic RandomRBFDrift dataset. We demonstrate that the quantum models under study are more susceptible to concept drift compared with their classical counterparts in the KDDCUP99 dataset. This is seen in the results as more severe drops with longer recovery duration exist in the prequential area under the curve (AUC) of the quantum models' receiver operating characteristics curve (ROC). On the other hand, comparable results are observed in the RandomRBFDrift dataset. As a mitigation strategy for concept drift in quantum models, we propose an optimal encoding strategy based on a genetic optimization that maximizes the AUC despite concept drift. The proposed strategy determines, based on the dataset, an optimal encoding of the classical data into quantum states using a combination of angle, amplitude, and basis encoding, optimal repetitions, circuit depth, etc. Our results demonstrate that the proposed strategy enhances the performance of the quantum models in the presence of concept drift, showcasing up to 5% improvement in the model accuracy. This study provides valuable insights into the effects and mitigation of concept drift in quantum machine learning and opens the door for future research.

Quantum Machine Learning (QML) has surfaced as a pioneering framework addressing sequential control tasks and time-series modeling. It has demonstrated empirical quantum advantages notably within domains such as Reinforcement Learning (RL) and time-series prediction. A significant advancement lies in Quantum Recurrent Neural Networks (QRNNs), specifically tailored for memory-intensive tasks encompassing partially observable environments and non-linear time-series prediction. Nevertheless, QRNN-based models encounter challenges, notably prolonged training duration stemming from the necessity to compute quantum gradients using backpropagation-through-time (BPTT). This predicament exacerbates when executing the complete model on quantum devices, primarily due to the substantial demand for circuit evaluation arising from the parameter-shift rule. This paper introduces the Quantum Fast Weight Programmers (QFWP) as a solution to the temporal or sequential learning challenge. The QFWP leverages a classical neural network (referred to as the ’slow programmer’) functioning as a quantum programmer to swiftly modify the parameters of a variational quantum circuit (termed the ’fast programmer’). Instead of completely overwriting the fast programmer at each time-step, the slow programmer generates parameter changes or updates for the quantum circuit parameters. This approach enables the fast programmer to incorporate past observations or information. Notably, the proposed QFWP model achieves learning of temporal dependencies without necessitating the use of quantum recurrent neural networks. Numerical simulations conducted in this study showcase the efficacy of the proposed QFWP model in both time-series prediction and RL tasks. The model exhibits performance levels either comparable to or surpassing those achieved by QLSTM-based models.

Recent advances in quantum computing (QC) and machine learning (ML) have drawn significant attention to the development of quantum machine learning (QML). Reinforcement learning (RL) is one of the ML paradigms which can be used to solve complex sequential decision making problems. Classical RL has been shown to be capable to solve various challenging tasks. However, RL algorithms in the quantum world are still in their infancy. One of the challenges yet to solve is how to train quantum RL in the partially observable environments. In this paper, we approach this challenge through building QRL agents with quantum recurrent neural networks (QRNN). Specifically, we choose the quantum long short-term memory (QLSTM) to be the core of the QRL agent and train the whole model with deep Q-learning. We demonstrate the results via numerical simulations that the QLSTM-DRQN can solve standard benchmark such as Cart-Pole with more stable and higher average scores than classical DRQN with similar architecture and number of model parameters.

Fast screening of drug molecules based on the ligand binding affinity is an important step in the drug discovery pipeline. Graph neural fingerprint is a promising method for developing molecular docking surrogates with high throughput and great fidelity. In this study, we built a COVID-19 drug docking dataset of about 300,000 drug candidates on 23 coronavirus protein targets. With this dataset, we trained graph neural fin-gerprint docking models for high-throughput virtual COVID-19 drug screening. The graph neural fingerprint models yield high prediction accuracy on docking scores with the mean squared error lower than 0.21 kcal/mol for most of the docking targets, showing significant improvement over conventional circular fin-gerprint methods. To make the neural fingerprints transferable for unknown targets, we also propose a transferable graph neural fingerprint method trained on multiple targets. With comparable accuracy to target-specific graph neural fingerprint models, the training and data efficiency of the transferable model is several times higher. We highlight that the impact of this study extends beyond COVID-19 dataset, as our approach for fast virtual ligand screening can be easily adapted and integrated into a general machine learning-accelerated pipeline to battle future bio-threats.

Long short-term memory (LSTM) is a kind of recurrent neural networks (RNN) for sequence and temporal dependency data modeling and its effectiveness has been extensively established. In this work, we propose a hybrid quantum-classical model of LSTM, which we dub QLSTM. We demonstrate that the proposed model successfully learns several kinds of temporal data. In particular, we show that for certain testing cases, this quantum version of LSTM converges faster, or equivalently, reaches a better accuracy, than its classical counterpart. Due to the variational nature of our approach, the requirements on qubit counts and circuit depth are eased, and our work thus paves the way toward implementing machine learning algorithms for sequence modeling such as natural language processing, speech recognition on noisy intermediate-scale quantum (NISQ) devices.

In this paper, we discuss the initial attempts at boosting understanding human language based on deep-learning models with quantum computing. We successfully train a quantum-enhanced Long Short-Term Memory network to perform the parts-of-speech tagging task via numerical simulations. Moreover, a quantum-enhanced Transformer is proposed to perform the sentiment analysis based on the existing dataset.

The rapid development of quantum computing has demonstrated many unique characteristics of quantum advantages, such as richer feature representation and more secured protection on model parameters. This work proposes a vertical federated learning architecture based on variational quantum circuits to demonstrate the competitive performance of a quantum-enhanced pre-trained BERT model for text classification. In particular, our proposed hybrid classical-quantum model consists of a novel random quantum temporal convolution (QTC) learning framework replacing some layers in the BERT-based decoder. Our experiments on intent classification show that our proposed BERT-QTC model attains competitive experimental results in the Snips and ATIS spoken language datasets. Particularly, the BERT-QTC boosts the performance of the existing quantum circuit-based language model in two text classification datasets by 1.57% and 1.52% relative improvements. Furthermore, BERT-QTC can be feasibly deployed on both existing commercial-accessible quantum computation hardware and CPU-based interface for ensuring data isolation.

We propose a novel decentralized feature extraction approach in federated learning to address privacy-preservation issues for speech recognition. It is built upon a quantum convolutional neural network (QCNN) composed of a quantum circuit encoder for feature extraction, and a recurrent neural network (RNN) based end-to-end acoustic model (AM). To enhance model parameter protection in a decentralized architecture, an input speech is first up-streamed to a quantum computing server to extract Mel-spectrogram, and the corresponding convolutional features are encoded using a quantum circuit algorithm with random parameters. The encoded features are then down-streamed to the local RNN model for the final recognition. The proposed decentralized framework takes advantage of the quantum learning progress to secure models and to avoid privacy leakage attacks. Testing on the Google Speech Commands Dataset, the proposed QCNN encoder attains a competitive accuracy of 95.12% in a decentralized model, which is better than the previous architectures using centralized RNN models with convolutional features. We also conduct an in-depth study of different quantum circuit encoder architectures to provide insights into designing QCNN-based feature extractors. Neural saliency analyses demonstrate a correlation between the proposed QCNN features, class activation maps, and input spectrograms. We provide an implementation for future studies.