This chapter deals with the study of quantum machine learning which aims to achieve a speedup over traditional machine learning for data analysis. Further, deciphering tensor network quantum machine learning models, variational quantum circuits for quantum machine learning models, near-optimal quantum algorithms for string problems, quantum neural network for time-series predictions, Information-theoretically secure quantum encryption, quantum methods of temporal space optimization for real-time IoT applications, network attack detection scheme based on variational quantum neural network and quantum convolutional neural network for data analysis have been highlighted.