2,497 research outputs found
Persistent spin current and entanglement in the anisotropic spin ring i
We investigate the ground state persistent spin current and the pair
entanglement in one-dimensional antiferromagnetic anisotropic Heisenberg ring
with twisted boundary conditions. Solving Bethe ansatz equations numerically,
we calculate the dependence of the ground state energy on the total magnetic
flux through the ring, and the resulting persistent current. Motivated by
recent development of quantum entanglement theory, we study the properties of
the ground state concurrence under the influence of the flux through the
anisotropic Heisenberg ring. We also include an external magnetic field and
discuss the properties of the persistent current and the concurrence in the
presence of the magnetic field.Comment: 5 pages, 8 figure
Theory of unconventional quantum Hall effect in strained graphene
We show through both theoretical arguments and numerical calculations that
graphene discerns an unconventional sequence of quantized Hall conductivity,
when subject to both magnetic fields (B) and strain. The latter produces
time-reversal symmetric pseudo/axial magnetic fields (b). The single-electron
spectrum is composed of two interpenetrating sets of Landau levels (LLs),
located at , . For , these
two sets of LLs have opposite \emph{chiralities}, resulting in {\em
oscillating} Hall conductivity between 0 and in electron and hole
doped system, respectively, as the chemical potential is tuned in the vicinity
of the neutrality point. The electron-electron interactions stabilize various
correlated ground states, e.g., spin-polarized, quantum spin-Hall insulators at
and near the neutrality point, and possibly the anomalous Hall insulating phase
at incommensurate filling . Such broken-symmetry ground states have
similarities as well as significant differences from their counterparts in the
absence of strain. For realistic strength of magnetic fields and interactions,
we present scaling of the interaction-induced gap for various Hall states
within the zeroth Landau level.Comment: 5 pages and 2 figures + supplementary (3.5 pages and 5 figures);
Published version, cosmetic changes and updated reference
Resource Destroying Maps
Resource theory is a widely-applicable framework for analyzing the physical
resources required for given tasks, such as computation, communication, and
energy extraction. In this paper, we propose a general scheme for analyzing
resource theories based on resource destroying maps, which leave resource-free
states unchanged but erase the resource stored in all other states. We
introduce a group of general conditions that determine whether a quantum
operation exhibits typical resource-free properties in relation to a given
resource destroying map. Our theory reveals fundamental connections among basic
elements of resource theories, in particular, free states, free operations, and
resource measures. In particular, we define a class of simple resource measures
that can be calculated without optimization, and that are monotone
nonincreasing under operations that commute with the resource destroying map.
We apply our theory to the resources of coherence and quantum correlations
(e.g., discord), two prominent features of nonclassicality.Comment: 12 pages including Supplemental Material, published versio
Bulk and edge quasihole tunneling amplitudes in the Laughlin state
The tunneling between the Laughlin state and its quasihole excitations are
studied by using the Jack polynomial. We find a universal analytical formula
for the tunneling amplitude, which can describe both bulk and edge quasihole
excitations. The asymptotic behavior of the tunneling amplitude reveals the
difference and the crossover between bulk and edge states. The effects of the
realistic coulomb interaction with a background-charge confinement potential
and disorder are also discussed. The stability of the tunneling amplitude
manifests the topological nature of fractional quantum Hall liquids.Comment: 9 pages, 1 figure
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