15 research outputs found
Quantum Phase Transitions for Bosons in One Dimension
We study the ground state phase diagram and the critical properties of
interacting Bosons in one dimension by means of a quantum Monte Carlo
technique. The direct experimental realization is a chain of Josephson
junctions. For finite-range interactions we find a novel intermediate phase
which shows neither solid order nor superfluidity. We determine the location of
this phase and study the critical behaviour of the various transitions. For
on-site interaction only, we map out the phase diagram as a function of the
hopping strength and the chemical potential.Comment: 11 pages, revtex, 2 eps-figure
Flux Noise near the Berezinskii-Kosterlitz-Thouless Transition
We study the flux noise in Josephson junction arrays in the critical regime
above the Berezinskii-Kosterlitz-Thouless transition. In proximity coupled
arrays a local ohmic damping for the phases is relevant, giving rise to
anomalous vortex diffusion and a dynamic scaling of the flux noise in the
critical region. It shows a crossover from white to -noise at a frequency
with a dynamic exponent .Comment: Revised version to be published in JETP Letter
Response of Josephson-junction arrays and granular superconductors near the superconductor-insulator transition
The Superconductor-Insulator Transition in a Tunable Dissipative Environment
We study the influence of a tunable dissipative environment on the dynamics
of Josephson junction arrays near the superconductor-insulator transition. The
experimental realization of the environment is a two dimensional electron gas
coupled capacitively to the array. This setup allows for the well-controlled
tuning of the dissipation by changing the resistance of the two dimensional
electron gas. The capacitive coupling cuts off the dissipation at low
frequencies. We determine the phase diagram and calculate the temperature and
dissipation dependence of the array conductivity. We find good agreement with
recent experimental results.Comment: 4 pages, 4 .eps figures, revte
On the Coexistence of Diagonal and off-Diagonal Long-Range Order, a Monte Carlo Study
The zero temperature properties of interacting 2 dimensional lattice bosons
are investigated. We present Monte Carlo data for soft-core bosons that
demonstrate the existence of a phase in which crystalline long-range order and
off-diagonal long-range order (superfluidity) coexist. We comment on the
difference between hard and soft-core bosons and compare our data to mean-field
results that predict a larger coexistence region. Furthermore, we determine the
critical exponents for the various phase transitions.Comment: 7 pages and 8 figures appended in postscript, KA-TFP-93-0