All our former experience with application of quantum theory seems to say that what is
predicted by quantum formalism must occur in the laboratory. But the essence of quantum …

How can one prove that a given quantum state is entangled? In this paper we review
different methods that have been proposed for entanglement detection. We first explain the …

Quantum information theory is a branch of science at the frontier of physics, mathematics,
and information science, and offers a variety of solutions that are impossible using classical …

This largely self-contained book on the theory of quantum information focuses on precise
mathematical formulations and proofs of fundamental facts that form the foundation of the …

The orbital angular momentum of light represents a fundamentally new optical degree of
freedom. Unlike linear momentum, or spin angular momentum, which is associated with the …

Quantum mechanics and information theory are among the most important scientific
discoveries of the last century. Although these two areas initially developed separately, it …

We analyze and compare the mathematical formulations of the criterion for separability for
bipartite density matrices and the Bell inequalities. We show that a violation of a Bell …

We present a toy theory that is based on a simple principle: the number of questions about
the physical state of a system that are answered must always be equal to the number that …

An entanglement witness (EW) is an operator that allows the detection of entangled states.
We give necessary and sufficient conditions for such operators to be optimal, ie, to detect …

We introduce a classification of mixed three-qubit states, in which we define the classes of
separable, biseparable, W, and Greenberger-Horne-Zeilinger states. These classes are …