Generic entangled states

Generic incomparability of infinite-dimensional entangled states

In support of a recent conjecture by Nielsen (1999), we prove that the phenomena of ‘incomparable entanglement’— whereby, neither member of a pair of pure entangled states can be transformed into the other via local operations and classical communication (LOCC)—is a generic feature when the states at issue live in an infinite-dimensional Hilbert space.  2002 Elsevier Science B.V. All rights re...

Representation of Entangled States

It is impossible to know the probability amplitudes of an unknown state, because if one could do so, one can clone the state. This means that identifying a pair of correlated qubits with the perfectly entangled state 1 2 (|00〉+ |11〉) is an idealization unless it is certified by tests on identically produced pairs from a coherent source. Questions related to the reference frame for measurement o...

Geometry of entangled states

Geometric properties of the set of quantum entangled states are investigated. We propose an explicit method to compute the dimension of local orbits for any mixed state of the general K3M problem and characterize the set of effectively different states ~which cannot be related by local transformations!. Thus, we generalize earlier results obtained for the simplest 232 system, which lead to a st...

Multipartite entangled coherent states

We propose a scheme for generating multipartite entangled coherent states via entanglement swapping, with an example of a physical realization in ion traps. Bipartite entanglement of these multipartite states is quantified by the concurrence. We also compute multipartite entanglement for certain systems. Finally we establish that these results for entanglement can be applied to more general mul...

Collective entangled dark states