2,697 research outputs found
Deconfined Quantum Critical Point on the Triangular Lattice
We first propose a topological term that captures the "intertwinement"
between the standard "" antiferromagnetic order (or
the so-called 120 state) and the "" valence
solid bond (VBS) order for spin-1/2 systems on a triangular lattice. Then using
a controlled renormalization group calculation, we demonstrate that there
exists an unfine-tuned direct continuous deconfined quantum critical point
(dQCP) between the two ordered phases mentioned above. This dQCP is described
by the quantum electrodynamics (QED) with an emergent
PSU(4)=SU(4)/ symmetry only at the critical point. The topological term
aforementioned is also naturally derived from the QED. We also point
out that physics around this dQCP is analogous to the boundary of a
bosonic symmetry protected topological state with on-site symmetries only
High-speed in vitro intensity diffraction tomography
We demonstrate a label-free, scan-free intensity diffraction tomography technique utilizing annular illumination (aIDT) to rapidly characterize large-volume three-dimensional (3-D) refractive index distributions in vitro. By optimally matching the illumination geometry to the microscope pupil, our technique reduces the data requirement by 60 times to achieve high-speed 10-Hz volume rates. Using eight intensity images, we recover volumes of βΌ350βΞΌmββΓββ100βΞΌmββΓββ20ββΞΌm, with near diffraction-limited lateral resolution of βββΌββ487ββnm and axial resolution of βββΌββ3.4ββΞΌm. The attained large volume rate and high-resolution enable 3-D quantitative phase imaging of complex living biological samples across multiple length scales. We demonstrate aIDTβs capabilities on unicellular diatom microalgae, epithelial buccal cell clusters with native bacteria, and live Caenorhabditis elegans specimens. Within these samples, we recover macroscale cellular structures, subcellular organelles, and dynamic micro-organism tissues with minimal motion artifacts. Quantifying such features has significant utility in oncology, immunology, and cellular pathophysiology, where these morphological features are evaluated for changes in the presence of disease, parasites, and new drug treatments. Finally, we simulate the aIDT system to highlight the accuracy and sensitivity of the proposed technique. aIDT shows promise as a powerful high-speed, label-free computational microscopy approach for applications where natural imaging is required to evaluate environmental effects on a sample in real time.https://arxiv.org/abs/1904.06004Accepted manuscrip
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Spin Echo and Interference in Synchrotrons
Spin dynamics in crossing a single depolarization resonance is a well-studied subject. One well-known example is that of Froissart and Stora in 1960. More is needed to complete the understanding, particularly of the transient effects, when crossing a single resonance, but question arises what happens if we cross two resonances or cross a single resonance twice. When a resonance is crossed twice, the particle's spin dynamics encounters two additional phenomena. First, the two crossings will interfere with each other, leading to an interference effect. Second, there will be a spin echo effect. We discuss these two effects in this report. Two proposals to test these effects experimentally are made at the end
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SLIM--An Early Work Revisited
An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981
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