72,078 research outputs found
Conditions for Nondistortion Interrogation of Quantum System
Under some physical considerations, we present a universal formulation to
study the possibility of localizing a quantum object in a given region without
disturbing its unknown internal state. When the interaction between the object
and probe wave function takes place only once, we prove the necessary and
sufficient condition that the object's presence can be detected in an initial
state preserving way. Meanwhile, a conditioned optimal interrogation
probability is obtained.Comment: 5 pages, Revtex, 1 figures, Presentation improved, corollary 1 added.
To appear in Europhysics Letter
Effect of Dzyaloshinskii Moriya interaction on magnetic vortex
The effect of the Dzyaloshinskii Moriya interaction on the vortex in magnetic
microdisk was investigated by micro magnetic simulation based on the Landau
Lifshitz Gilbert equation. Our results show that the DM interaction modifies
the size of the vortex core, and also induces an out of plane magnetization
component at the edge and inside the disk. The DM interaction can destabilizes
one vortex handedness, generate a bias field to the vortex core and couple the
vortex polarity and chirality. This DM-interaction-induced coupling can
therefore provide a new way to control vortex polarity and chirality
Chaotic Properties of Subshifts Generated by a Non-Periodic Recurrent Orbit
The chaotic properties of some subshift maps are investigated. These
subshifts are the orbit closures of certain non-periodic recurrent points of a
shift map. We first provide a review of basic concepts for dynamics of
continuous maps in metric spaces. These concepts include nonwandering point,
recurrent point, eventually periodic point, scrambled set, sensitive dependence
on initial conditions, Robinson chaos, and topological entropy. Next we review
the notion of shift maps and subshifts. Then we show that the one-sided
subshifts generated by a non-periodic recurrent point are chaotic in the sense
of Robinson. Moreover, we show that such a subshift has an infinite scrambled
set if it has a periodic point. Finally, we give some examples and discuss the
topological entropy of these subshifts, and present two open problems on the
dynamics of subshifts
Coherent output of photons from coupled superconducting transmission line resonators controlled by charge qubits
We study the coherent control of microwave photons propagating in a
superconducting waveguide consisting of coupled transmission line resonators,
each of which is connected to a tunable charge qubit. While these coupled line
resonators form an artificial photonic crystal with an engineered photonic band
structure, the charge qubits collectively behave as spin waves in the low
excitation limit, which modify the band-gap structure to slow and stop the
microwave propagation. The conceptual exploration here suggests an
electromagnetically controlled quantum device based on the on-chip circuit QED
for the coherent manipulation of photons, such as the dynamic creation of
laser-like output from the waveguide by pumping the artificial atoms for
population inversion.Comment: 8 pages, 3 figure
Consistent picture for the electronic structure around a vortex core in iron-based superconductors
Based on a two-orbital model and taking into account the presence of the
impurity, we studied theoretically the electronic structure in the vortex core
of the iron-Pnictide superconducting materials. The vortex is pinned when the
impurity is close to the vortex core. The bound states shows up for the
unpinned vortex and are wiped out by a impurity. Our results are in good
agreement with recent experiments and present a consistent explanation for the
different electronic structure of vortex core revealed by experiments on
different materials.Comment: 4 pages, 5 figure
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