When an initially entangled pair of qubits undergoes local decoherence processes, there are a number of ways in which the original entanglement can spread throughout the multipartite system consisting of the two qubits and their environments. Here, we report theoretical and experimental results regarding the dynamics of the distribution of entanglement in this system. The experiment employs an ...

The holographic representation of the entanglement entropy of four dimensional conformal field theories is studied. By generalizing the replica trick the anomalous terms in the entanglement entropy are evaluated. The same terms in the holographic representation are calculated by a method which does not require the solution of the equations of motion or a cut off. The two calculations disagree f...

A general inequality between entanglement entropy and a number of topologically ordered states is derived, even without using the properties of the parent Hamiltonian or the formalism of topological quantum field theory. Given a quantum state |ψ], we obtain an upper bound on the number of distinct states that are locally indistinguishable from |ψ]. The upper bound is determined only by the enta...

This paper is an exploration of the role of unitary braiding operators in quantum computing. We show that a single specific solution R of the Yang-Baxter Equation is a universal gate for quantum computing, in the presence of local unitary transformations. We show that this same R generates a new non-trivial invariant of braids, knots, and links. The paper discusses these results in the context ...

In this communication we introduce a new model which represents the interaction between an atom and two fields injected simultaneously within a cavity including the nonlinear couplers. By using the canonical transformation the model can be regarded as a generalization of several well known models. We calculate and discuss entanglement between the tripartite system of one atom and the two cavity...

We investigate the dynamical behavior of the atom-photon entanglement in a V-type three-level quantum system using the atomic reduced entropy. It is shown that an atom and photons are entangled at the steady-state; however disentanglement can also be achieved in an special condition. It is demonstrated that in the presence of quantum interference induced by spontaneous emission, the reduced ent...

Abstract A 9×9 unitary R̆−matrix, solution of the Yang-Baxter Equation, is obtained in this paper. The entanglement properties of R̆−matrix is investigated, and the arbitrary degree of entanglement for two-qutrit entangled states can be generated via R̆-matrix acting on the standard basis. A Yang-Baxter Hamiltonian can be constructed from unitary R̆−matrix. Then the geometric properties of this sys...

We investigate how entanglement can be transferred between continuous variable and qubit systems. We find that a two-mode squeezed vacuum state and a continuous variable Werner state can be converted to the product states of infinitive number of two-qubit states while keeping the entanglement. The reverse process is also possible. PACS: 03.67.Mn;03.65.Ud

ABSTRACT: Quantum information sheds new light on quantum systems, complementary to the traditional point of view of energy. A key notion is entanglement, which measures quantum correlations within the system. Understanding entanglement of ground states is crucial to efficiently represent such many-body states using a small number of variational parameters. This is but one example of very powerf...

Using well known duality between quantum maps and states of composite systems we introduce the notion of Schmidt number of a quantum channel. It enables one to define classes of quantum channels which partially break quantum entanglement. These classes generalize the well known class of entanglement breaking channels.