37,117 research outputs found
Soliton Staircases and Standing Strain Waves in Confined Colloidal Crystals
We show by computer simulation of a two-dimensional crystal confined by
corrugated walls that confinement can be used to impose a controllable
mesoscopic superstructure of predominantly mechanical elastic character. Due to
an interplay of the particle density of the system and the width D of the
confining channel, "soliton staircases" can be created along both parallel
confining boundaries, that give rise to standing strain waves in the entire
crystal. The periodicity of these waves is of the same order as D. This
mechanism should be useful for structure formation in the self-assembly of
various nanoscopic materials.Comment: 22 pages, 5 figure
Quantum simulation of the wavefunction to probe frustrated Heisenberg spin systems
Quantum simulators are controllable quantum systems that can reproduce the
dynamics of the system of interest, which are unfeasible for classical
computers. Recent developments in quantum technology enable the precise control
of individual quantum particles as required for studying complex quantum
systems. Particularly, quantum simulators capable of simulating frustrated
Heisenberg spin systems provide platforms for understanding exotic matter such
as high-temperature superconductors. Here we report the analog quantum
simulation of the ground-state wavefunction to probe arbitrary Heisenberg-type
interactions among four spin-1/2 particles . Depending on the interaction
strength, frustration within the system emerges such that the ground state
evolves from a localized to a resonating valence-bond state. This spin-1/2
tetramer is created using the polarization states of four photons. The
single-particle addressability and tunable measurement-induced interactions
provide us insights into entanglement dynamics among individual particles. We
directly extract ground-state energies and pair-wise quantum correlations to
observe the monogamy of entanglement
Neural Networks for Modeling and Control of Particle Accelerators
We describe some of the challenges of particle accelerator control, highlight
recent advances in neural network techniques, discuss some promising avenues
for incorporating neural networks into particle accelerator control systems,
and describe a neural network-based control system that is being developed for
resonance control of an RF electron gun at the Fermilab Accelerator Science and
Technology (FAST) facility, including initial experimental results from a
benchmark controller.Comment: 21 p
- …