6,357 research outputs found
A superfluid-droplet crystal and a free-space supersolid in a dipole-blockaded gas
A novel supersolid phase is predicted for an ensemble of Rydberg atoms in the
dipole-blockade regime, interacting via a repulsive dipolar potential
"softened" at short distances. Using exact numerical techniques, we study the
low temperature phase diagram of this system, and observe an intriguing phase
consisting of a crystal of mesoscopic superfluid droplets. At low temperature,
phase coherence throughout the whole system, and the ensuing bulk
superfluidity, are established through tunnelling of identical particles
between neighbouring droplets.Comment: 4 pages, 4 figure
Strongly correlated gases of Rydberg-dressed atoms: quantum and classical dynamics
We discuss techniques to generate long-range interactions in a gas of
groundstate alkali atoms, by weakly admixing excited Rydberg states with laser
light. This provides a tool to engineer strongly correlated phases with reduced
decoherence from inelastic collisions and spontaneous emission. As an
illustration, we discuss the quantum phases of dressed atoms with dipole-dipole
interactions confined in a harmonic potential, as relevant to experiments. We
show that residual spontaneous emission from the Rydberg state acts as a
heating mechanism, leading to a quantum-classical crossover.Comment: 4 pages, 4 figure
A stop-start study of solid propellants Final report
Thermal properties and chemical kinetics of solid phase in combustion process of ammonium perchlorate propellants during steady state and transient pressure condition
Strongly correlated 2D quantum phases with cold polar molecules: controlling the shape of the interaction potential
We discuss techniques to tune and shape the long-range part of the
interaction potentials in quantum gases of polar molecules by dressing
rotational excitations with static and microwave fields. This provides a novel
tool towards engineering strongly correlated quantum phases in combination with
low dimensional trapping geometries. As an illustration, we discuss a 2D
crystalline phase, and a superfluid-crystal quantum phase transition.Comment: 4 pages, 3 figure
On the IR behaviour of the Landau-gauge ghost propagator
We examine analytically the ghost propagator Dyson-Schwinger Equation (DSE)
in the deep IR regime and prove that a finite ghost dressing function at
vanishing momentum is an alternative solution (solution II) to the usually
assumed divergent one (solution I). We furthermore find that the Slavnov-Taylor
identities discriminate between these two classes of solutions and strongly
support the solution II. The latter turns out to be also preferred by lattice
simulations within numerical uncertainties.Comment: 15 pages, Axodraw neede
A Ghost Story: Ghosts and Gluons in the IR regime of QCD
We discuss the different methods to obtain reliable informations about the
deep infra-red behaviour of the gluon and ghost Green functions in QCD. We
argue that a clever combination of analytical inputs and numerical ones is
necessary. We illustrate this statement about the distinction between two
classes of solutions of the ghost propagator Dyson-Schwinger equation (GPDSE).
We conclude that the solution II ("decoupling") with a finite renormalised
ghost dressing function at zero momentum is strongly favored by lattice QCD, We
derive a method to solve numerically the GPDSE using lattice inputs concerning
the gluon propagator. We derive an analytical small momentum expansion of the
Ghost dressing function. We prove from the large cut-off behaviour of the ghost
propagator renormalisation constant, , that the bare ghost
dressing function is infinite at the infinite cut-off limit.Comment: 12 pages 6 figure
- …