Summary:
In this Thesis we study quantum entanglement in the context of quantum
information. Entangled quantum systems exhibit non-local correlations, useful
in many applications of quantum cryptography, communication and computing,
since they allow for quantum teleportation, super-dense coding etc. Thus, it's
natural that we search for ways to extract this property from systems at finite
temperature, in which entanglement exists but is of no use. We study the ideal
bosonic field at finite temperature, trapped in a 3D infinite square well, and
we find that its spatial degrees of freedom are entangled even though they
abstain a spacelike distance. We send two independent and distinguishable
two-level quantum systems to interact with different spatial degrees of freedom
of the field for a short time. After the interaction, even though they never
interacted with each other, we find the two systems to be entangled. We
quantify the entanglement and show that it exists only when the field's
temperature is near the absolute zero. Having absorbed the entanglement, the
two systems are can now be exploited for various quantum information tasks.
Keywords:
Quantum, Information, Entanglement , Field, Extraction
