379 research outputs found
Trimer liquids and crystals of polar molecules in coupled wires
We investigate the pairing and crystalline instabilities of bosonic and
fermionic polar molecules confined to a ladder geometry. By means of analytical
and quasi-exact numerical techniques, we show that gases of composite molecular
dimers as well as trimers can be stabilized as a function of the density
difference between the wires. A shallow optical lattice can pin both liquids,
realizing crystals of composite bosons or fermions. We show that these exotic
quantum phases should be realizable under current experimental conditions in
finite-size confining potentials.Comment: 5 pages, 3 figures plus additional material; Accepted for publication
in Phys. Rev. Let
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 lattice of double wells for manipulating pairs of cold atoms
We describe the design and implementation of a 2D optical lattice of double
wells suitable for isolating and manipulating an array of individual pairs of
atoms in an optical lattice. Atoms in the square lattice can be placed in a
double well with any of their four nearest neighbors. The properties of the
double well (the barrier height and relative energy offset of the paired sites)
can be dynamically controlled. The topology of the lattice is phase stable
against phase noise imparted by vibrational noise on mirrors. We demonstrate
the dynamic control of the lattice by showing the coherent splitting of atoms
from single wells into double wells and observing the resulting double-slit
atom diffraction pattern. This lattice can be used to test controlled neutral
atom motion among lattice sites and should allow for testing controlled
two-qubit gates.Comment: 9 pages, 11 figures Accepted for publication in Physical Review
Scalable register initialization for quantum computing in an optical lattice
The Mott insulator state created by loading an atomic Bose-Einstein
condensate (BEC) into an optical lattice may be used as a means to prepare a
register of atomic qubits in a quantum computer. Such architecture requires a
lattice commensurately filled with atoms, which corresponds to the insulator
state only in the limit of zero inter-well tunneling. We show that a lattice
with spatial inhomogeneity created by a quadratic magnetic trapping potential
can be used to isolate a subspace in the center which is impervious to
hole-hoping. Components of the wavefunction with more than one atom in any well
can be projected out by selective measurement on a molecular photo-associative
transition. Maintaining the molecular coupling induces a quantum Zeno effect
that can sustain a commensurately filled register for the duration of a quantum
computation.Comment: 5 pages, 2 figure
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