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 …

Consider three qubits A, B, and C which may be entangled with each other. We show that
there is a trade-off between A's entanglement with B and its entanglement with C. This …

The introduction of control theory in quantum mechanics has created a rich, new
interdisciplinary scientific field, which is producing novel insight into important theoretical …

We define a polynomial measure of multiparticle entanglement which is scalable, ie, which
applies to any number of spin-1/2 particles. By evaluating it for three particle states, for …

We study nonlocal two-qubit operations from a geometric perspective. By applying a Cartan
decomposition to su (4), we find that the geometric structure of nonlocal gates is a 3-torus …

The theory of quantum information, that is, of the transmission, storage, and processing of
information using quantum-mechanical systems, is now well developed. It has been …

Entanglement of two parts of a quantum system is a nonlocal property unaffected by local
manipulations of these parts. It can be described by quantities invariant under local unitary …

We give quantum circuits that simulate an arbitrary two-qubit unitary operator up to a global
phase. For several quantum gate libraries we prove that gate counts are optimal in the worst …