9,283 research outputs found
A Modified Optical Potential Approach to Low-energy Electron-helium Scattering
Optical potential approach to low energy electron- helium scatterin
Number-conserving interacting fermion models with exact topological superconducting ground states
We present a method to construct number-conserving Hamiltonians whose ground
states exactly reproduce an arbitrarily chosen BCS-type mean-field state. Such
parent Hamiltonians can be constructed not only for the usual -wave BCS
state, but also for more exotic states of this form, including the ground
states of Kitaev wires and 2D topological superconductors. This method leads to
infinite families of locally-interacting fermion models with exact topological
superconducting ground states. After explaining the general technique, we apply
this method to construct two specific classes of models. The first one is a
one-dimensional double wire lattice model with Majorana-like degenerate ground
states. The second one is a two-dimensional superconducting model,
where we also obtain analytic expressions for topologically degenerate ground
states in the presence of vortices. Our models may provide a deeper conceptual
understanding of how Majorana zero modes could emerge in condensed matter
systems, as well as inspire novel routes to realize them in experiment.Comment: 5 pages, 2 figures; supplement: 4 pages, 1 figur
Quantum state transmission via a spin ladder as a robust data bus
We explore the physical mechanism to coherently transfer the quantum
information of spin by connecting two spins to an isotropic antiferromagnetic
spin ladder system as data bus. Due to a large spin gap existing in such a
perfect medium, the effective Hamiltonian of the two connected spins can be
archived as that of Heisenberg type, which possesses a ground state with
maximal entanglement. We show that the effective coupling strength is inversely
proportional to the distance of the two spins and thus the quantum information
can be transferred between the two spins separated by a longer distance, i.e.
the characteristic time of quantum state transferring linearly depends on the
distance.Comment: 7 pages, 5 figures, 1 tabl
The effect of hidden color channels on nucleon-nucleon interaction in quark model
In the framework of constituent quark model, the effect of hidden color
channels on the nucleon-nucleon () interaction is studied. By adjusting the
color confinement strength between the hidden color channels and color singlet
channels and/or between the hidden color channels and hidden color channels,
the experimental data of to partial-wave phase shifts of
scattering can be fitted well. The results show that the hidden color channel
coupling might be important in producing the intermediate-range attraction of
interaction. The deuteron properties and dibaryon candidates have also
been studied with this model.Comment: 11 pages, 9 figure
Density oscillations in trapped dipolar condensates
We investigated the ground state wave function and free expansion of a
trapped dipolar condensate. We find that dipolar interaction may induce both
biconcave and dumbbell density profiles in, respectively, the pancake- and
cigar-shaped traps. On the parameter plane of the interaction strengths, the
density oscillation occurs only when the interaction parameters fall into
certain isolated areas. The relation between the positions of these areas and
the trap geometry is explored. By studying the free expansion of the condensate
with density oscillation, we show that the density oscillation is detectable
from the time-of-flight image.Comment: 7 pages, 9 figure
Structural phase transitions of vortex matter in an optical lattice
We consider the vortex structure of a rapidly rotating trapped atomic
Bose-Einstein condensate in the presence of a co-rotating periodic optical
lattice potential. We observe a rich variety of structural phases which reflect
the interplay of the vortex-vortex and vortex-lattice interactions. The lattice
structure is very sensitive to the ratio of vortices to pinning sites and we
observe structural phase transitions and domain formation as this ratio is
varied.Comment: 4 pages, 3 figure
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