6,565 research outputs found
Cavity-QED entangled photon source based on two truncated Rabi oscillations
We discuss a cavity-QED scheme to deterministically generate entangled
photons pairs by using a three-level atom successively coupled to two single
longitudinal mode high-Q cavities presenting polarization degeneracy. The first
cavity is prepared in a well defined Fock state with two photons with opposite
circular polarizations while the second cavity remains in the vacuum state. A
half-of-a-resonant Rabi oscillation in each cavity transfers one photon from
the first to the second cavity, leaving the photons entangled in their
polarization degree of freedom. The feasibility of this implementation and some
practical considerations are discussed for both, microwave and optical regimes.
In particular, Monte Carlo wave function simulations have been performed with
state-of-the-art parameter values to evaluate the success probability of the
cavity-QED source in producing entangled photon pairs as well as its
entanglement capability.Comment: 18 pages, 9 figures; submitted for the "Optical Quantum Information
Science Special Issue" of JOSA
Chiral Spin Textures of Strongly Interacting Particles in Quantum Dots
We probe for statistical and Coulomb induced spin textures among the
low-lying states of repulsively-interacting particles confined to potentials
that are both rotationally and time-reversal invariant. In particular, we focus
on two-dimensional quantum dots and employ configuration-interaction techniques
to directly compute the correlated many-body eigenstates of the system. We
produce spatial maps of the single-particle charge and spin density and verify
the annular structure of the charge density and the rotational invariance of
the spin field. We further compute two-point spin correlations to determine the
correlated structure of a single component of the spin vector field. In
addition, we compute three-point spin correlation functions to uncover chiral
structures. We present evidence for both chiral and quasi-topological spin
textures within energetically degenerate subspaces in the three- and
four-particle system.Comment: 13 pages, 17 figures, 1 tabl
A temperature behavior of the frustrated translational mode of adsorbate and the nature of the "adsorbate-substrate" interaction
A temperature behavior of the frustrated translational mode (T-mode) of a
light particle, coupled by different regimes of ohmicity to the surface, is
studied within a formalism of the generalized diffusion coefficients. The
memory effects of the adsorbate motion are considered to be the main reason of
the T-mode origin. Numerical calculations yield a thermally induced shift and
broadening of the T-mode, which is found to be linear in temperature for Ohmic
and super-Ohmic systems and nonlinear for strongly sub-Ohmic ones. We obtain
analytical expressions for the T-mode shift and width at weak coupling for the
systems with integer "ohmicity" indexes n=0-2 in zero temperature and high
temperature limits. We provide an explanation of the experimentally observed
blue- or red-shifts of the T-mode on the basis of a comparative analysis of two
typical times of the system evolution: a time of decay of the
"velocity-velocity" autocorrelation function, and a correlation time of the
thermal bath random forces. A relation of the T-mode to the multiple jumps of
the adsorbate is discussed, and generalization of conditions of the multiple
hopping to the case of quantum surface diffusion is performed.Comment: 12 pages, 4 figure
Thermodynamics of Quantum-Jump-Conditioned Feedback Control
We consider open quantum systems weakly coupled to thermal reservoirs and
subjected to quantum feedback operations triggered with or without delay by
monitored quantum jumps. We establish a thermodynamic description of such
system and analyze how the first and second law of thermodynamics are modified
by the feedback. We apply our formalism to study the efficiency of a qubit
subjected to a quantum feedback control and operating as a heat pump between
two reservoirs. We also demonstrate that quantum feedbacks can be used to
stabilize coherences in nonequilibrium stationary states which in some cases
may even become pure quantum states.Comment: 12 pages, 6 figure
Photon transport in a dissipative chain of nonlinear cavities
We analyze a chain of coupled nonlinear optical cavities driven by a coherent
source of light localized at one end and subject to uniform dissipation. We
characterize photon transport by studying the populations and the photon
correlations as a function of position. When complemented with input-output
theory, these quantities provide direct information about photon transmission
through the system. The position of single- and multi-photon resonances
directly reflect the structure of the many-body energy levels. This shows how a
study of transport along a coupled cavity array can provide rich information
about the strongly correlated (many-body) states of light even in presence of
dissipation. By means of a numerical algorithm based on the time-evolving block
decimation scheme adapted to mixed states, we are able to simulate arrays up to
sixty cavities.Comment: 12 pages, 14 figure
Systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes with the Gogny energy density functional
The systematics of one-quasiparticle configurations in neutron-rich Sr, Zr,
and Mo odd isotopes is studied within the Hartree-Fock-Bogoliubov plus Equal
Filling Approximation method preserving both axial and time reversal
symmetries. Calculations based on the Gogny energy density functional with both
the standard D1S parametrization and the new D1M incarnation of this functional
are included in our analysis. The nuclear deformation and shape coexistence
inherent to this mass region are shown to play a relevant role in the
understanding of the spectroscopic features of the ground and low-lying
one-quasineutron states.Comment: 11 page
- …