2,389 research outputs found
Edge excitations of the Chern Simons matrix theory for the FQHE
We study the edge excitations of the Chern Simons matrix theory, describing
the Laughlin fluids for filling fraction , with an
integer. Based on the semiclassical solutions of the theory, we are able to
identify the bulk and edge degrees of freedom. In this way we can freeze the
bulk of the theory, to the semiclassical values, obtaining an effective theory
governing the boundary excitations of the Chern Simons matrix theory. Finally,
we show that this effective theory is equal to the chiral boson theory on the
circle.Comment: 22 pages. Section 3.2. improved. 2 Appendices added. Accepted for
publication in JHE
Entanglement entropy of integer Quantum Hall states
We compute the entanglement entropy, in real space, of the ground state of
the integer Quantum Hall states for three different domains embedded in the
torus, the disk and the sphere. We establish the validity of the area law with
a vanishing value of the topological entanglement entropy. The entropy per unit
length of the perimeter depends on the filling fraction, but it is independent
of the geometry.Comment: 5 pages, 2 figures, minor changes, one reference adde
Neural-Network Quantum States, String-Bond States, and Chiral Topological States
Neural-Network Quantum States have been recently introduced as an Ansatz for
describing the wave function of quantum many-body systems. We show that there
are strong connections between Neural-Network Quantum States in the form of
Restricted Boltzmann Machines and some classes of Tensor-Network states in
arbitrary dimensions. In particular we demonstrate that short-range Restricted
Boltzmann Machines are Entangled Plaquette States, while fully connected
Restricted Boltzmann Machines are String-Bond States with a nonlocal geometry
and low bond dimension. These results shed light on the underlying architecture
of Restricted Boltzmann Machines and their efficiency at representing many-body
quantum states. String-Bond States also provide a generic way of enhancing the
power of Neural-Network Quantum States and a natural generalization to systems
with larger local Hilbert space. We compare the advantages and drawbacks of
these different classes of states and present a method to combine them
together. This allows us to benefit from both the entanglement structure of
Tensor Networks and the efficiency of Neural-Network Quantum States into a
single Ansatz capable of targeting the wave function of strongly correlated
systems. While it remains a challenge to describe states with chiral
topological order using traditional Tensor Networks, we show that
Neural-Network Quantum States and their String-Bond States extension can
describe a lattice Fractional Quantum Hall state exactly. In addition, we
provide numerical evidence that Neural-Network Quantum States can approximate a
chiral spin liquid with better accuracy than Entangled Plaquette States and
local String-Bond States. Our results demonstrate the efficiency of neural
networks to describe complex quantum wave functions and pave the way towards
the use of String-Bond States as a tool in more traditional machine-learning
applications.Comment: 15 pages, 7 figure
Matrix Effective Theories of the Fractional Quantum Hall effect
The present understanding of nonperturbative ground states in the
fractional quantum Hall effect is based on effective theories of the Jain \composite
fermion" excitations. We review the approach based on matrix variables, i.e. D0
branes, originally introduced by Susskind and Polychronakos. We show that the
Maxwell-Chern-Simons matrix gauge theory provides a matrix generalization of the
quantum Hall effect, where the composite-fermion construction naturally follows from
gauge invariance. The matrix ground states obtained by suitable projections of higher
Landau levels are found to be in one-to-one correspondence with the Laughlin and
Jain hierarchical states. The matrix theory possesses a physical limit for commuting
matrices that could be reachable while staying in the same phase
Frequency-selective near-field enhancement of radiative heat transfer via photonic-crystal slabs: a general computational approach for arbitrary geometries and materials
We demonstrate the possibility of achieving enhanced frequency-selective
near-field radiative heat transfer between patterned (photonic crystal) slabs
at designable frequencies and separations, exploiting a general numerical
approach for computing heat transfer in arbitrary geometries and materials
based on the finite-difference time-domain method. Our simulations reveal a
tradeoff between selectivity and near-field enhancement as the slab--slab
separation decreases, with the patterned heat transfer eventually reducing to
the unpatterned result multiplied by a fill factor (described by a standard
proximity approximation). We also find that heat transfer can be further
enhanced at selective frequencies when the slabs are brought into a
glide-symmetric configuration, a consequence of the degeneracies associated
with the non-symmorphic symmetry group
Safe Drone Flight with Time-Varying Backup Controllers
The weight, space, and power limitations of small aerial vehicles often
prevent the application of modern control techniques without significant model
simplifications. Moreover, high-speed agile behavior, such as that exhibited in
drone racing, make these simplified models too unreliable for safety-critical
control. In this work, we introduce the concept of time-varying backup
controllers (TBCs): user-specified maneuvers combined with backup controllers
that generate reference trajectories which guarantee the safety of nonlinear
systems. TBCs reduce conservatism when compared to traditional backup
controllers and can be directly applied to multi-agent coordination to
guarantee safety. Theoretically, we provide conditions under which TBCs
strictly reduce conservatism, describe how to switch between several TBC's and
show how to embed TBCs in a multi-agent setting. Experimentally, we verify that
TBCs safely increase operational freedom when filtering a pilot's actions and
demonstrate robustness and computational efficiency when applied to
decentralized safety filtering of two quadrotors.Comment: Submitted to IROS 202
ATOS: Integration of advanced technology software within distributed Spacecraft Mission Operations Systems
The Advanced Technology Operations System (ATOS) is a program of studies into the integration of advanced applications (including knowledge based systems (KBS)) with ground systems for the support of spacecraft mission operations
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