Entanglement percolation in quantum networks

Abstract

Quantum entanglement is a phenomenon in which two or more systems interact in such a way that the quantum state of the entire system cannot be expressed as a probabilistic mixture of pure product quantum states of the individual systems even when the systems are far away. The correlations in an entangled state are of a quite different nature and there is no classical analogy to them [24,26]. Entanglement is a very valuable resource for a variety of quantum information applications and has been applied to develop very useful protocols like teleportation [12], dense coding [11], quantum key distribution [9, 10] and entanglement swapping [4, 13]. Quantum Entanglement also has widespread applications in large-scale communication. It can be applied for effective long distance communication. It is thus essential to understand the non-trivial task of creating and distributing entanglement between distant parties. The subject is greatly complicated, largely due to the fact that entanglement is a very fragile resource, in the sense that it inevitably deteriorates while being manipulated or being stored [24]. This report introduces the strategies for establishing long distance entanglement distribution in quantum networks, building upon from the basics of entanglement manipulation and then presenting the details of entanglement distribution through entanglement swapping and entanglement percolation. The last chapter of the thesis deals with the devising of another measurement strategy in a quantum network which may help entanglement percolation succeed with the usage of a lower amount of resources.