Quantum entanglement, a phenomenon in quantum mechanics where the quantum states of two or more objects become correlated, has emerged as a key concept with wide-ranging implications in modern physics. This paper provides a comprehensive review of quantum entanglement, covering its fundamentals, experimental demonstrations, and applications. The paper begins with an introduction to quantum mechanics and the definition of entanglement, highlighting its importance in modern physics. It then explores the fundamentals of entangled states, Bell states, and entanglement measures, with a focus on the mathematical description and experimental demonstrations. The paper also discusses the applications of quantum entanglement in quantum computing, quantum communication, and quantum sensing, highlighting the role of entanglement in enabling quantum technologies. Finally, the paper examines the challenges and future directions in the field, including scalability issues, noise, decoherence, and integration with classical systems. Overall, this paper provides a comprehensive overview of quantum entanglement and its significance in advancing quantum technologies.

quantum entanglement, quantum mechanics, entangled states, Bell states, quantum computing, quantum communication, quantum sensing, scalability, noise, decoherence, integration.