1,806 research outputs found
Local response of topological order to an external perturbation
We study the behavior of the R\'enyi entropies for the toric code subject to
a variety of different perturbations, by means of 2D density matrix
renormalization group and analytical methods. We find that R\'enyi entropies of
different index {\alpha} display derivatives with opposite sign, as opposed to
typical symmetry breaking states, and can be detected on a very small subsystem
regardless of the correlation length. This phenomenon is due to the presence in
the phase of a point with flat entanglement spectrum, zero correlation length,
and area law for the entanglement entropy. We argue that this kind of splitting
is common to all the phases with a certain group theoretic structure, including
quantum double models, cluster states, and other quantum spin liquids. The fact
that the size of the subsystem does not need to scale with the correlation
length makes it possible for this effect to be accessed experimentally.Comment: updated to published versio
Geological survey of Maryland using EREP flight data
The author has identified the following significant results. Underflight photography has been used in the Baltimore County mined land inventory to determine areas of disturbed land where surface mining of sand and ground clay, or stone has taken place. Both active and abandoned pits and quarries were located. Aircraft data has been used to update cultural features of Calvert, Caroline, St. Mary's, Somerset, Talbot, and Wicomico Counties. Islands have been located and catalogued for comparison with older film and map data for erosion data. Strip mined areas are being mapped to obtain total area disturbed to aid in future mining and reclamation problems. Coastal estuarine and Atlantic Coast features are being studied to determine nearshore bedforms, sedimentary, and erosional patterns, and manmade influence on natural systems
Lieb-Robinson bounds for commutator-bounded operators
We generalize the Lieb-Robinson theorem to systems whose Hamiltonian is the
sum of local operators whose commutators are bounded.Comment: 5 pages, minor editorial change
Magnonic triply-degenerate nodal points
We generalize the concept of triply-degenerate nodal points to non-collinear
antiferromagnets. Here, we introduce this concept to insulating quantum
antiferromagnets on the decorated honeycomb lattice, with spin- bosonic
quasiparticle excitations known as magnons. We demonstrate the existence of
magnonic surface states with constant energy contours that form pairs of
magnonic arcs connecting the surface projection of the magnonic triple nodal
points. The quasiparticle excitations near the triple nodal points represent
three-component bosons beyond that of magnonic Dirac, Weyl, and nodal-line
cases. They can be regarded as a direct reflection of the intrinsic spin
carried by magnons. Furthermore, we show that the magnonic triple nodal points
can split into magnonic Weyl points, as the system transits from a
non-collinear spin structure to a noncoplanar one with a nonzero scalar spin
chirality. Our results not only apply to insulating antiferromagnets, but also
provide a platform to seek for triple nodal points in metallic
antiferromagnets.Comment: 6 pages, 5 figures + Supplemental Material. To appear in EPL
(Europhys. Lett.
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