Continuous-variable multipartite unlockable bound entangled Gaussian states

Continuous-variable (CV) multipartite unlockable bound-entangled states is investigated in this paper. Comparing with the qubit multipartite unlockable bound-entangled states, CV multipartite unlockable bound-entangled states present the new and different properties. CV multipartite unlockable bound-entangled states may serve as a useful quantum resource for new multiparty communication schemes. The experimental protocol for generating CV unlockable bound-entangled states is proposed with a setup that is at present accessible.Comment: 6 pages, 4 figure

Graphical description of local Gaussian operations for continuous-variable weighted graph states

The form of a local Clifford (LC, also called local Gaussian (LG)) operation for the continuous-variable (CV) weighted graph states is presented in this paper, which is the counterpart of the LC operation of local complementation for qubit graph states. The novel property of the CV weighted graph states is shown, which can be expressed by the stabilizer formalism. It is distinctively different from the qubit weighted graph states, which can not be expressed by the stabilizer formalism. The corresponding graph rule, stated in purely graph theoretical terms, is described, which completely characterizes the evolution of CV weighted graph states under this LC operation. This LC operation may be applied repeatedly on a CV weighted graph state, which can generate the infinite LC equivalent graph states of this graph state. This work is an important step to characterize the LC equivalence class of CV weighted graph states.Comment: 5 pages, 6 figure

Confinement induced by fermion damping in three-dimensional QED

The three-dimensional non-compact QED is known to exhibit weak confinement when fermions acquire a finite mass via the mechanism of dynamical chiral symmetry breaking. In this paper, we study the effect of fermion damping caused by elastic scattering on the classical potential between fermions. By calculating the vacuum polarization function that incorporates the fermion damping effect, we show that fermion damping can induce a weak confinement even when the fermions are massless and the chiral symmetry is not broken.Comment: 4 pages, no figur

Quantum optomechanics of a Bose-Einstein Antiferromagnet

We investigate the cavity optomechanical properties of an antiferromagnetic Bose-Einstein con- densate, where the role of the mechanical element is played by spin-wave excitations. We show how this system can be described by a single rotor that can be prepared deep in the quantum regime under realizable experimental conditions. This system provides a bottom-up realization of dispersive rotational optomechanics, and opens the door to the direct observation of quantum spin fluctuations.Comment: 4 pages, 1 figure, accepted for publication in Physical Review Letters (2011