9,812 research outputs found
Stability of Bloch Oscillations in two coupled Bose-Einstein condensates
We investigate analytically, the stability of Bloch waves at the boundary of
the first Brillouin zone in two coupled Bose-Einstein condensates confined in
an optical lattice. Contrary to the single component case, we find here two
critical density regimes which determine the stability of the Bloch waves.
Breakdown of Bloch oscillations appear when n1/n2Nc2, here
Nc1 and Nc2 are some critical values of n1/n2. There is an intermediate regime
between Nc1 and Nc2 where the Bloch oscillations are stable and the condensates
behave like single particles
Generalized contact process with two symmetric absorbing states in two dimensions
We explore the two-dimensional generalized contact process with two absorbing
states by means of large-scale Monte-Carlo simulations. In part of the phase
diagram, an infinitesimal creation rate of active sites between inactive
domains is sufficient to take the system from the inactive phase to the active
phase. The system therefore displays two different nonequilibrium phase
transitions. The critical behavior of the generic transition is compatible with
the generalized voter (GV) universality class, implying that the
symmetry-breaking and absorbing transitions coincide. In contrast, the
transition at zero domain-boundary activation rate is not critical.Comment: 7 pages, 7 eps figures included, final version as publishe
Multiparty Quantum Secret Sharing
Based on a quantum secure direct communication (QSDC) protocol [Phys. Rev.
A69(04)052319], we propose a -threshold scheme of multiparty quantum
secret sharing of classical messages (QSSCM) using only single photons. We take
advantage of this multiparty QSSCM scheme to establish a scheme of multiparty
secret sharing of quantum information (SSQI), in which only all quantum
information receivers collaborate can the original qubit be reconstructed. A
general idea is also proposed for constructing multiparty SSQI schemes from any
QSSCM scheme
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