975 research outputs found
Defects in the Tri-critical Ising model
We consider two different conformal field theories with central charge
c=7/10. One is the diagonal invariant minimal model in which all fields have
integer spins; the other is the local fermionic theory with superconformal
symmetry in which fields can have half-integer spin. We construct new conformal
(but not topological or factorised) defects in the minimal model. We do this by
first constructing defects in the fermionic model as boundary conditions in a
fermionic theory of central charge c=7/5, using the folding trick as first
proposed by Gang and Yamaguchi. We then acting on these with interface defects
to find the new conformal defects. As part of the construction, we find the
topological defects in the fermionic theory and the interfaces between the
fermionic theory and the minimal model. We also consider the simpler case of
defects in the theory of a single free fermion and interface defects between
the Ising model and a single fermion as a prelude to calculations in the
tri-critical Ising model.Comment: 54 pages, 5 figures, version as accepted for publication with minor
change
The reflection coefficient for minimal model conformal defects from perturbation theory
We consider a class of conformal defects in Virasoro minimal models that have
been defined as fixed points of the renormalisation group and calculate the
leading contribution to the reflection coefficient for these defects. This
requires several structure constants of the operator algebra of the defect
fields, for which we present a derivation in detail. We compare our results
with our recent work on conformal defects in the tricritical Ising model.Comment: 22 pages; v2: minor changes, defect field transformation law
clarified, reference adde
U(1) symmetry breaking in one-dimensional Mott insulator studied by the Density Matrix Renormalization Group method
A new type of external fields violating the particle number preservation is
studied in one-dimensional strongly correlated systems by the Density Matrix
Renormalization Group method. Due to the U(1) symmetry breaking, the ground
state has fluctuation of the total particle number, which implies injection of
electrons and holes from out of the chain. This charge fluctuation can be
relevant even at half-filling because the particle-hole symmetry is preserved
with the finite effective field. In addition, we discuss a quantum phase
transition obtained by considering the symmetry-breaking fields as a mean field
of interchain-hopping.Comment: 7 pages, 4 figure
Topological quantum phase transition in the BEC-BCS crossover phenomena
A crossover between the Bose Einstein condensation (BEC) and BCS
superconducting state is described topologically in the chiral symmetric
fermion system with attractive interaction. Using a local Z_2 Berry phase, we
found a quantum phase transition between the BEC and BCS phases without
accompanying the bulk gap closing.Comment: 4 pages, 5 figure
Fabrication of submicron LaSrCuO intrinsic Josephson junction stacks
Intrinsic Josephson junction (IJJ) stacks of cuprate superconductors have
potential to be implemented as intrinsic phase qubits working at relatively
high temperatures. We report success in fabricating submicron
LaSrCuO (LSCO) IJJ stacks carved out of single crystals. We
also show a new fabrication method in which argon ion etching is performed
after focused ion beam etching. As a result, we obtained an LSCO IJJ stack in
which resistive multi-branches appeared. It may be possible to control the
number of stacked IJJs with an accuracy of a single IJJ by developing this
method.Comment: 5 pages, 6 figure
Neutron scattering study on spin correlations and fluctuations in the transition-metal-based magnetic quasicrystal Zn-Fe-Sc
Spin correlations and fluctuations in the 3d-transition-metal-based
icosahedral quasicrystal Zn-Fe-Sc have been investigated by neutron scattering
using polycrystalline samples. Magnetic diffuse scattering has been observed in
the elastic experiment at low temperatures, indicating development of static
short-range-spin correlations. In addition, the inelastic scattering experiment
detects a -independent quasielastic signal ascribed to single-site
relaxational spin fluctuations. Above the macroscopic freezing temperature
K, the spin relaxation rate shows Arrhenius-type behavior,
indicating thermally activated relaxation process. In contrast, the relaxation
rate remains finite even at the lowest temperature, suggesting a certain
quantum origin for the spin fluctuations below .Comment: To be published in Phys. Rev.
Production of uniform droplets using membrane, microchannel and microfluidic emulsification devices
This review provides an overview of major microengineering emulsification techniques for production of monodispersed droplets. The main emphasis has been put on membrane emulsification using Shirasu Porous Glass and microsieve membrane, microchannel emulsification using grooved-type and straight-through microchannel plates, microfluidic junctions and flow focusing microfluidic devices. Microfabrication methods for production of planar and 3D poly(dimethylsiloxane) devices, glass capillary microfluidic devices and single-crystal silicon microchannel array devices have been described including soft lithography, glass capillary pulling and microforging, hot embossing, anisotropic wet etching and deep reactive ion etching. In addition, fabrication methods for SPG and microseive membranes have been outlined, such as spinodal decomposition, reactive ion etching and ultraviolet LIGA (Lithography, Electroplating, and Moulding) process. The most widespread application of micromachined emulsification devices is in the synthesis of monodispersed particles and vesicles, such as polymeric particles, microgels, solid lipid particles, Janus particles, and functional vesicles (liposomes, polymersomes and colloidosomes). Glass capillary microfluidic devices are very suitable for production of core/shell drops of controllable shell thickness and multiple emulsions containing a controlled number of inner droplets and/or inner droplets of two or more distinct phases. Microchannel emulsification is a very promising technique for production of monodispersed droplets with droplet throughputs of up to 100 l h−1
Theorems on ground-state phase transitions in Kohn-Sham models given by the Coulomb density functional
Some theorems on derivatives of the Coulomb density functional with respect
to the coupling constant are given. Consider an electron density
given by a ground state. A model Fermion system with the
reduced coupling constant, , is defined to reproduce and the ground state energy. Fixing the charge density, possible phase
transitions as level crossings detected in a value of the reduced density
functional happen only at discrete points along the axis. If the
density is -representable also for , accumulation of phase
transition points is forbidden when . Relevance of the
theorems for the multi-reference density functional theory is discussed.Comment: 19 page
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