Quantum Internet - Applications, Functionalities, Enabling Technologies, Challenges, and Research Directions

The advanced notebooks, mobile phones, and Internet applications in today's world that we use are all entrenched in classical communication bits of zeros and ones. Classical Internet has laid its foundation originating from the amalgamation of mathematics and Claude Shannon's theory of information. However, today's Internet technology is a playground for eavesdroppers. This poses a serious challenge to various applications that rely on classical Internet technology, and it has motivated the researchers to switch to new technologies that are fundamentally more secure. By exploring the quantum effects, researchers paved the way into quantum networks that provide security, privacy, and range of capabilities such as quantum computation, communication, and metrology. The realization of Quantum Internet (QI) requires quantum communication between various remote nodes through quantum channels guarded by quantum cryptographic protocols. Such networks rely upon quantum bits (qubits) that can simultaneously take the value of zeros and ones. Due to the extraordinary properties of qubits such as superposition, entanglement, and teleportation, it gives an edge to quantum networks over traditional networks in many ways. At the same time, transmitting qubits over long distances is a formidable task and extensive research is going on satellite-based quantum communication, which will deliver breakthroughs for physically realizing QI in near future. In this paper, QI functionalities, technologies, applications and open challenges have been extensively surveyed to help readers gain a basic understanding of the infrastructure required for the development of the global QI.