Classification is a core application of quantum machine learning. This study aims at the problems existing in current pure quantum classifiers, such as the large number of consumed qubits and the unsatisfactory performance in multi-classification tasks. Based on the flexible representation of quantum images (FRQI), a new quantum circuit model QCCE that can be used for multi-classification tasks is constructed by introducing additional measurement qubits and connecting them to the color qubit bits. This model not only inherits the encoding advantages of FRQI, enabling it to encode high-dimensional image inputs with a relatively small number of qubits, but also has all trainable parameters in the quantum circuit, with classical computing only providing the loss function and optimizer. Experiments on datasets such as MNIST and Fashion MNIST have shown that in multi-classification tasks like three, four, and five-class classifications, the QCCE model demonstrates obvious advantages over similar quantum circuit models such as HEA and MORE in terms of classification accuracy and convergence speed. The research in this study provides new ideas and methods for the application of quantum machine learning in image processing.
Classification is a core application of quantum machine learning. This study aims at the problems existing in current pure quantum classifiers, such as the large number of consumed qubits and the unsatisfactory performance in multi-classification tasks. Based on the flexible representation of quantum images (FRQI), a new quantum circuit model QCCE that can be used for multi-classification tasks is constructed by introducing additional measurement qubits and connecting them to the color qubit bits. This model not only inherits the encoding advantages of FRQI, enabling it to encode high-dimensional image inputs with a relatively small number of qubits, but also has all trainable parameters in the quantum circuit, with classical computing only providing the loss function and optimizer. Experiments on datasets such as MNIST and Fashion MNIST have shown that in multi-classification tasks like three, four, and five-class classifications, the QCCE model demonstrates obvious advantages over similar quantum circuit models such as HEA and MORE in terms of classification accuracy and convergence speed. The research in this study provides new ideas and methods for the application of quantum machine learning in image processing.
Abstract Image classification, a pivotal task in multiple industries, faces computational challenges due to the burgeoning volume of visual data. This research addresses these challenges by introducing two quantum machine learning models that leverage the principles of quantum mechanics for effective computations. Our first model, a hybrid quantum neural network with parallel quantum circuits, enables the execution of computations even in the noisy intermediate-scale quantum era, where circuits with a large number of qubits are currently infeasible. This model demonstrated a record-breaking classification accuracy of 99.21% on the full MNIST dataset, surpassing the performance of known quantum–classical models, while having eight times fewer parameters than its classical counterpart. Also, the results of testing this hybrid model on a Medical MNIST (classification accuracy over 99%), and on CIFAR-10 (classification accuracy over 82%), can serve as evidence of the generalizability of the model and highlights the efficiency of quantum layers in distinguishing common features of input data. Our second model introduces a hybrid quantum neural network with a Quanvolutional layer, reducing image resolution via a convolution process. The model matches the performance of its classical counterpart, having four times fewer trainable parameters, and outperforms a classical model with equal weight parameters. These models represent advancements in quantum machine learning research and illuminate the path towards more accurate image classification systems.
Image classification is an important task in many practical applications. Recently, there have been various works on classification problems using quantum neural network (QNN). Different data encoders have been investigated, but efficient quantum encoding schemes for high-dimensional data such as images are still an open question. In this study, we investigate popular representation formats of quantum images, namely FRQI and NEQR, as data encoders for quantum neural networks. It is found that the FRQI format not only provides the best classification accuracy compared to NEQR and other popular encoding methods but also is consistent across different circuit depths of QNN. It should be noted that FRQI is notorious for its probabilistic representation in quantum image processing. The finding of this study is interesting because FRQI can play an important role in the field of quantum machine learning.
Quantum machine learning (QML) has attracted significant research attention over the last decade. Multiple models have been developed to demonstrate the practical applications of the quantum properties. In this study, we first demonstrate that the previously proposed quanvolutional neural network (QuanvNN) using a randomly generated quantum circuit improves the image classification accuracy of a fully connected neural network against the Modified National Institute of Standards and Technology (MNIST) dataset and the Canadian Institute for Advanced Research 10 class (CIFAR-10) dataset from 92.0% to 93.0% and from 30.5% to 34.9%, respectively. We then propose a new model referred to as a Neural Network with Quantum Entanglement (NNQE) using a strongly entangled quantum circuit combined with Hadamard gates. The new model further improves the image classification accuracy of MNIST and CIFAR-10 to 93.8% and 36.0%, respectively. Unlike other QML methods, the proposed method does not require optimization of the parameters inside the quantum circuits; hence, it requires only limited use of the quantum circuit. Given the small number of qubits and relatively shallow depth of the proposed quantum circuit, the proposed method is well suited for implementation in noisy intermediate-scale quantum computers. While promising results were obtained by the proposed method when applied to the MNIST and CIFAR-10 datasets, a test against a more complicated German Traffic Sign Recognition Benchmark (GTSRB) dataset degraded the image classification accuracy from 82.2% to 73.4%. The exact causes of the performance improvement and degradation are currently an open question, prompting further research on the understanding and design of suitable quantum circuits for image classification neural networks for colored and complex data.
Quantum neural networks, which combine quantum computing and machine learning, have become a topic of great interest due to the advancement of quantum computing. This paper introduces a pure quantum neural network model based on parameterized quantum circuits, applied to image classification using the Iris dataset. Experimental validation demonstrates superior classification accuracy in three-class tasks. Specifically, this paper innovatively uses IQP encoding to encode classical data into quantum states, and independently designs the Ansatz in the quantum neural network. Experimental results show that compared with the other three classical classification algorithms and four quantum neural network models, the pure quantum neural network model proposed in the study has the highest accuracy in image classification tasks. In addition, this article analyzes and evaluates the model’s expression characteristics and entanglement capabilities, providing a reference for further optimizing and expanding the quantum neural network model. Overall, this research provides new ideas and methods for the integration of quantum computing and machine learning, which has certain practical value and research significance.
Multiclass classification is of great interest for various applications, for example, it is a common task in computer vision, where one needs to categorize an image into three or more classes. Here we propose a quantum machine learning approach based on quantum convolutional neural networks for solving the multiclass classification problem. The corresponding learning procedure is implemented via TensorFlowQuantum as a hybrid quantum-classical (variational) model, where quantum output results are fed to the softmax activation function with the subsequent minimization of the cross entropy loss via optimizing the parameters of the quantum circuit. Our conceptional improvements here include a new model for a quantum perceptron and an optimized structure of the quantum circuit. We use the proposed approach to solve a 4-class classification problem for the case of the MNIST dataset using eight qubits for data encoding and four ancilla qubits; previous results have been obtained for 3-class classification problems. Our results show that the accuracy of our solution is similar to classical convolutional neural networks with comparable numbers of trainable parameters. We expect that our findings will provide a new step toward the use of quantum neural networks for solving relevant problems in the NISQ era and beyond.
The domain of image classification has been seen to be dominated by high-performing deep-learning (DL) architectures. However, the success of this field, as seen over the past decade, has resulted in the complexity of modern methodologies scaling exponentially, commonly requiring millions of parameters. Quantum computing (QC) is an active area of research aimed toward greatly reducing problems of complexity faced in classical computing. With growing interest toward quantum machine learning (QML) for applications of image classification, many proposed algorithms require usage of numerous qubits. In the noisy intermediate-scale quantum (NISQ) era, these circuits may not always be feasible to execute effectively; therefore, we should aim to use each qubit as effectively and efficiently as possible, before adding additional qubits. This article proposes a new single-qubit-based deep quantum neural network for image classification that mimics traditional convolutional neural network (CNN) techniques, resulting in a reduced number of parameters compared with previous works. Our aim is to prove the concept of the initial proposal by demonstrating classification performance of the single-qubit-based architecture, as well as to provide a tested foundation for further development. To demonstrate this, our experiments were conducted using various datasets including MNIST, Fashion-MNIST, and ORL face datasets. To further our proposal in the context of the NISQ era, our experiments were intentionally conducted in noisy simulation environments. Initial test results appear promising, with classification accuracies of 94.6%, 89.5%, and 82.5% achieved on the subsets of MNIST, FMNIST, and ORL face datasets, respectively. In addition, proposals for further investigation and development were considered, where it is hoped that these initial results can be improved.