3,271 research outputs found
On the Absence of Cross-Confinement for Dynamically Generated Multi-Chern-Simons Theories
We show that when the induced parity breaking part of the effective action
for the low-momentum region of U(1) x ... x U(1) Maxwell gauge field theory
with massive fermions in 3 dimensions is coupled to a \phi^4 scalar field
theory, it is not possible to eliminate the screening of the long-range Coulomb
interactions and get external charges confined in the broken Higgs phase. This
result is valid for non-zero temperature as well.Comment: 7 pages, LaTe
Comparison of formaldehyde columns observed with aircraft and the SCIAMACHY and OMI satellite instruments during the 2006 AMMA campaign
Wigner crystals in two-dimensional transition-metal dichalcogenides: Spin physics and readout
Wigner crystals are prime candidates for the realization of regular electron
lattices under minimal requirements on external control and electronics.
However, several technical challenges have prevented their detailed
experimental investigation and applications to date. We propose an
implementation of two-dimensional electron lattices for quantum simulation of
Ising spin systems based on self-assembled Wigner crystals in transition-metal
dichalcogenides. We show that these semiconductors allow for minimally invasive
all-optical detection schemes of charge ordering and total spin. For incident
light with optimally chosen beam parameters and polarization, we predict a
strong dependence of the transmitted and reflected signals on the underlying
lattice periodicity, thus revealing the charge order inherent in Wigner
crystals. At the same time, the selection rules in transition-metal
dichalcogenides provide direct access to the spin degree of freedom via Faraday
rotation measurements.Comment: 15 pages, 12 figure
Non-locality of non-Abelian anyons
Topological systems, such as fractional quantum Hall liquids, promise to
successfully combat environmental decoherence while performing quantum
computation. These highly correlated systems can support non-Abelian anyonic
quasiparticles that can encode exotic entangled states. To reveal the non-local
character of these encoded states we demonstrate the violation of suitable Bell
inequalities. We provide an explicit recipe for the preparation, manipulation
and measurement of the desired correlations for a large class of topological
models. This proposal gives an operational measure of non-locality for anyonic
states and it opens up the possibility to violate the Bell inequalities in
quantum Hall liquids or spin lattices.Comment: 7 pages, 3 figure
Defect mediated melting and the breaking of quantum double symmetries
In this paper, we apply the method of breaking quantum double symmetries to
some cases of defect mediated melting. The formalism allows for a systematic
classification of possible defect condensates and the subsequent confinement
and/or liberation of other degrees of freedom. We also show that the breaking
of a double symmetry may well involve a (partial) restoration of an original
symmetry. A detailed analysis of a number of simple but representative examples
is given, where we focus on systems with global internal and external (space)
symmetries. We start by rephrasing some of the well known cases involving an
Abelian defect condensate, such as the Kosterlitz-Thouless transition and
one-dimensional melting, in our language. Then we proceed to the non-Abelian
case of a hexagonal crystal, where the hexatic phase is realized if
translational defects condense in a particular rotationally invariant state.
Other conceivable phases are also described in our framework.Comment: 10 pages, 4 figures, updated reference
Effects of laser parameters and scanning strategy on structural and mechanical properties of 3D NiTi implants fabricated with selective laser melting
A non-abelian spin-liquid in a spin-1 quantum magnet
We study a time-reversal invariant non-abelian spin-liquid state in an symmetric spin quantum magnet on a triangular lattice. The
spin-liquid is obtained by quantum disordering a non-collinear nematic state.
We show that such a spin-liquid cannot be obtained by the standard projective
construction for spin-liquids. We also study phase transition between the
spin-liquid and the non-collinear nematic state and show that it cannot be
described within Landau-Ginzburg- Wilson paradigm.Comment: 4.25 pages, 1 figur
Qudit surface codes and gauge theory with finite cyclic groups
Surface codes describe quantum memory stored as a global property of
interacting spins on a surface. The state space is fixed by a complete set of
quasi-local stabilizer operators and the code dimension depends on the first
homology group of the surface complex. These code states can be actively
stabilized by measurements or, alternatively, can be prepared by cooling to the
ground subspace of a quasi-local spin Hamiltonian. In the case of spin-1/2
(qubit) lattices, such ground states have been proposed as topologically
protected memory for qubits. We extend these constructions to lattices or more
generally cell complexes with qudits, either of prime level or of level
for prime and , and therefore under tensor
decomposition, to arbitrary finite levels. The Hamiltonian describes an exact
gauge theory whose excitations
correspond to abelian anyons. We provide protocols for qudit storage and
retrieval and propose an interferometric verification of topological order by
measuring quasi-particle statistics.Comment: 26 pages, 5 figure
From spin to anyon notation: The XXZ Heisenberg model as a (or ) anyon chain
We discuss a relationship between certain one-dimensional quantum spin chains
and anyon chains. In particular we show how the XXZ Heisenberg chain is
realised as a (alternately ) anyon model. We find the
difference between the models lie primarily in choice of boundary condition.Comment: 13 page
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