4 research outputs found
Estimating Patterns of Classical and Quantum Skyrmion States
In this review we discuss the latest results concerning development of the
machine learning algorithms for characterization of the magnetic skyrmions that
are topologically-protected magnetic textures originated from the
Dzyaloshinskii-Moriya interaction that competes Heisenberg isotropic exchange
in ferromagnets. We show that for classical spin systems there is a whole pool
of machine approaches allowing their accurate phase classification and
quantitative description on the basis of few magnetization snapshots. In turn,
investigation of the quantum skyrmions is a less explored issue, since there
are fundamental limitations on the simulation of such wave functions with
classical supercomputers. One needs to find the ways to imitate quantum
skyrmions on near-term quantum computers. In this respect, we discuss
implementation of the method for estimating structural complexity of classical
objects for characterization of the quantum skyrmion state on the basis of
limited number of bitstrings obtained from the projective measurements
An effective spin model on the honeycomb lattice for the description of magnetic properties in two-dimensional FeGeTe
FeGeTe attracts significant attention due to technological
perspectives of realizing room temperature ferromagnetism in two-dimensional
materials. Here we show that due to structural peculiarities of the
FeGeTe monolayer, short distance between the neighboring iron atoms
induces a strong exchange coupling. This strong coupling allows us to consider
them as an effective cluster with a magnetic moment 5 , giving
rise to a simplified spin model on a bipartite honeycomb lattice with the
reduced number of long-range interactions. The simplified model perfectly
reproduces the results of the conventional spin model, but allows for a more
tractable description of the magnetic properties of FeGeTe, which is
important, e.g., for large-scale simulations. Also, we discuss the role of
biaxial strain in the stabilization of ferromagnetic ordering in
FeGeTe.Comment: 7 pages, 7 figure
Field evolution of the spin-liquid candidate YbMgGaO4
We report magnetization, heat capacity, thermal expansion, and
magnetostriction measurements down to mK temperatures on the triangular
antiferromagnet YbMgGaO. Our data exclude the formation of the distinct
-plateau phase observed in other triangular antiferromagnets, but
reveal plateau-like features in second derivatives of the free energy, magnetic
susceptibility and specific heat, at = 1.0 - 2.5 T for
and 2 - 5 T for . Using Monte-Carlo simulations of a realistic spin
Hamiltonian, we ascribe these features to non-monotonic changes in the
magnetization and the -plateau that is smeared out by the random
distribution of exchange couplings in YbMgGaO
Benchmarking a boson sampler with Hamming nets
Analyzing the properties of complex quantum systems is crucial for further
development of quantum devices, yet this task is typically challenging and
demanding with respect to required amount of measurements. A special attention
to this problem appears within the context of characterizing outcomes of noisy
intermediate-scale quantum devices, which produce quantum states with specific
properties so that it is expected to be hard to simulate such states using
classical resources. In this work, we address the problem of characterization
of a boson sampling device, which uses interference of input photons to produce
samples of non-trivial probability distributions that at certain condition are
hard to obtain classically. For realistic experimental conditions the problem
is to probe multi-photon interference with a limited number of the measurement
outcomes without collisions and repetitions. By constructing networks on the
measurements outcomes, we demonstrate a possibility to discriminate between
regimes of indistinguishable and distinguishable bosons by quantifying the
structures of the corresponding networks. Based on this we propose a
machine-learning-based protocol to benchmark a boson sampler with unknown
scattering matrix. Notably, the protocol works in the most challenging regimes
of having a very limited number of bitstrings without collisions and
repetitions. As we expect, our framework can be directly applied for
characterizing boson sampling devices that are currently available in
experiments.Comment: 14 page