99 research outputs found
Bound states of skyrmions and merons near the Lifshitz point
We study topological defects in anisotropic ferromagnets with competing
interactions near the Lifshitz point. We show that skyrmions and bi-merons are
stable in a large part of the phase diagram. We calculate skyrmion-skyrmion and
meron-meron interactions and show that skyrmions attract each other and form
ring-shaped bound states in a zero magnetic field. At the Lifshitz point merons
carrying a fractional topological charge become deconfined. These results imply
that unusual topological excitations may exist in weakly frustrated magnets
with conventional crystal lattices.Comment: 5 pages, 4 figure
Revealing quantum chaos with machine learning
Understanding properties of quantum matter is an outstanding challenge in
science. In this paper, we demonstrate how machine-learning methods can be
successfully applied for the classification of various regimes in
single-particle and many-body systems. We realize neural network algorithms
that perform a classification between regular and chaotic behavior in quantum
billiard models with remarkably high accuracy. We use the variational
autoencoder for autosupervised classification of regular/chaotic wave
functions, as well as demonstrating that variational autoencoders could be used
as a tool for detection of anomalous quantum states, such as quantum scars. By
taking this method further, we show that machine learning techniques allow us
to pin down the transition from integrability to many-body quantum chaos in
Heisenberg XXZ spin chains. For both cases, we confirm the existence of
universal W shapes that characterize the transition. Our results pave the way
for exploring the power of machine learning tools for revealing exotic
phenomena in quantum many-body systems.Comment: 12 pages, 12 figure
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