Quantifying Quantum Entanglement.
Quantum entanglement has played a very important role in quantum
information theory; it provides strong tests of quantum nonlocality as
well as a useful resource for various kinds of quantum information
processing. It is really important to describe quantum entanglement both
qualitatively and quantitatively. What kinds of states are entangled? To
answer this question, we present a necessary and sufficient criterion
for multipartite entangled states; this criterion is particularly useful
when the density matrix of the given quantum states has few nonzero eigenvalues. If a quantum state is entangled, then, how much
entanglement does it contain? It will be shown that, a scalar number
cannot quantify quantum entanglement, unlike temperature. The
entanglement types and possible ways for entanglement quantification
will also be discussed.
Department of Physics and Astronomy
University of South Carolina, Columbia