Quantum phases in mixtures of fermionic atoms

A mixture of spin-polarized light and heavy fermionic atoms on a finite size 2D optical lattice is considered at various temperatures and values of the coupling between the two atomic species. In the case, where the heavy atoms are immobile in comparison to the light atoms, this system can be seen as a correlated binary alloy related to the Falicov-Kimball model. The heavy atoms represent a scattering environment for the light atoms. The distributions of the binary alloy are discussed in terms of strong- and weak-coupling expansions. We further present numerical results for the intermediate interaction regime and for the density of states of the light particles. The numerical approach is based on a combination of a Monte-Carlo simulation and an exact diagonalization method. We find that the scattering by the correlated heavy atoms can open a gap in the spectrum of the light atoms, either for strong interaction or small temperatures.Comment: 15 pages, 8 figure

Mixtures of fermionic atoms in an optical lattice

A mixture of light and heavy spin-polarized fermionic atoms in an optical lattice is considered. Tunneling of the heavy atoms is neglected such that they are only subject to thermal fluctuations. This results in a complex interplay between light and heavy atoms caused by quantum tunneling of the light atoms. The distribution of the heavy atoms is studied. It can be described by an Ising-like distribution with a first-order transition from homogeneous to staggered order. The latter is caused by an effective nonlocal interaction due to quantum tunneling of the light atoms. A second-order transition is also possible between an ordered and a disordered phase of the heavy atoms

A gene therapy approach for treating muscle degeneration in neuromuscular disorders using IGF-I splice variants.

Neuromuscular disorders, which associate with muscle degeneration, are not rare and affect millions of people worldwide. The impacts of such disorders vary from gradual loss of mobility and independence to severe disability and death, and therefore millions of patients suffer from them at every stage of their life. Because, there is currently no treatment of any form of such disorders, this study was aimed to develop a novel treatment for such disorders. For a long time it has been known that Insulin-like Growth Factor (IGF-I) influences several cellular processes, including proliferation, differentiation, repair and maintenance. Like many genes, the IGF-I gene can be spliced to produce several isoforms, and in human muscle, it expresses at least two main isoforms which are a liver type, systemic form (IGF-I Ea) and an autocrine / paracrine form (IGF-I Ec). This second isoform has been named the Mechano Growth Factor (MGF) because of its mechanosensitivity. The in vitro and in vivo effects of these two splice variants of the IGF-I gene were investigated in this study. In vitro roles of two splice variants of the gene were studied by the proliferation / differentiation effects of two alternative splice isoforms of the gene in animal muscle cell lines (mouse C2C12 and rat L6 E9). Proliferation / differentiation assays were carried out using human primary cell cultures from biopsied muscles from congenital muscular dystrophy (CMD), fascioscapulohumeral muscular dystrophy (FSHD) and amyotrophic lateral sclerosis (ALS) patients as well as from healthy volunteers. Human primary muscle cells were treated with IGF-I Ea (long r IGF-I) and MGF E domain peptides, and immunocytochemistry techniques with Desmin, DAPI and FITC markers were used to detect proliferation state of myogenic commitment. The CPK and BCA protein assays were also used to determine the differentiation state following such peptide treatments. The results showed that MGF significantly increased muscle stem (satellite) cell proliferation in both animal and human muscles, both in healthy and in severe muscle wasting disorders. E domain of MGF dramatically increased proliferation in progenitor cell in CMD (68%), FSHD (74%) and ALS (49%) primary cultures. The results also confirmed that the MGF had no effect on myotube formation but that it increases myoblast progenitor cell proliferation, whilst systemic IGF-I peptide (IGF-I Ea) increased cell differentiation and facilitated myotube formation. The effects of two IGF-I splice variants in muscle fibre growth were also studied in relation to Duchenne Muscular Dystrophy (DMD) by in vivo gene transfer method using the mdx mouse model. Such effects were investigated in both young and old mdx mice TA muscles by intramuscular injection of cDNAs in plasmid vectors pcDNA3.1NT/GFP. Maximum muscle tetanic contractile force was measured to determine the changes of muscle strength at 21 days after gene injection. The results showed that cDNA of MGF dramatically increased muscle fibre strength in young mdx mice (37 %) in only 3 weeks time. The MGF also increased muscle strength and mass in the older mdx mice but to a moderate level (11%). In mdx mice, the changes in gene expressions of satellite cell markers (MyoD and myogenin) were determined by quantitative real-time reverse transcriptase PCR, 21 days after injection of the gene constructs into TA muscle comparing with TA muscle of untreated leg. The results showed that MGF had an effect in satellite cell activation, and it activated quiescent satellite cells in mdx mice. This study showed that MGF has a significant effect in both in vitro and in vivo models, which were used in relation to treatment of muscle degeneration in DMD, CMD, FSHD and ALS. The study also showed that MGF has considerable potential to use as a therapeutic agent to treat muscle degeneration in such neuromuscular disorders

Si_3N_4 optomechanical crystals in the resolved-sideband regime

We demonstrate sideband-resolved optomechanical crystals supporting 10^5 quality factor optical modes at 980 nm, coupled to  GHz frequency mechanical modes with quality factors of ≈3000. Optomechanical electromagnetically induced transparency and absorption are observed at room temperature and in atmosphere with intracavity photon numbers in excess of 10^4

Efficient out-coupling of high-purity single photons from a coherent quantum dot in a photonic-crystal cavity

We demonstrate a single-photon collection efficiency of $(44.3\pm2.1)\%$ from a quantum dot in a low-Q mode of a photonic-crystal cavity with a single-photon purity of $g^{(2)}(0)=(4\pm5)\%$ recorded above the saturation power. The high efficiency is directly confirmed by detecting up to $962\pm46$ kilocounts per second on a single-photon detector on another quantum dot coupled to the cavity mode. The high collection efficiency is found to be broadband, as is explained by detailed numerical simulations. Cavity-enhanced efficient excitation of quantum dots is obtained through phonon-mediated excitation and under these conditions, single-photon indistinguishability measurements reveal long coherence times reaching $0.77\pm0.19$ ns in a weak-excitation regime. Our work demonstrates that photonic crystals provide a very promising platform for highly integrated generation of coherent single photons including the efficient out-coupling of the photons from the photonic chip.Comment: 13 pages, 8 figures, submitte

HSTR-Net: Reference Based Video Super-resolution for Aerial Surveillance with Dual Cameras

Aerial surveillance requires high spatio-temporal resolution (HSTR) video for more accurate detection and tracking of objects. This is especially true for wide-area surveillance (WAS), where the surveyed region is large and the objects of interest are small. This paper proposes a dual camera system for the generation of HSTR video using reference-based super-resolution (RefSR). One camera captures high spatial resolution low frame rate (HSLF) video while the other captures low spatial resolution high frame rate (LSHF) video simultaneously for the same scene. A novel deep learning architecture is proposed to fuse HSLF and LSHF video feeds and synthesize HSTR video frames at the output. The proposed model combines optical flow estimation and (channel-wise and spatial) attention mechanisms to capture the fine motion and intricate dependencies between frames of the two video feeds. Simulations show that the proposed model provides significant improvement over existing reference-based SR techniques in terms of PSNR and SSIM metrics. The method also exhibits sufficient frames per second (FPS) for WAS when deployed on a power-constrained drone equipped with dual cameras.Comment: 15 pages, 8 figures, 8 table

Improving the performance of bright quantum dot single photon sources using amplitude modulation

Single epitaxially-grown semiconductor quantum dots have great potential as single photon sources for photonic quantum technologies, though in practice devices often exhibit non-ideal behavior. Here, we demonstrate that amplitude modulation can improve the performance of quantum-dot-based sources. Starting with a bright source consisting of a single quantum dot in a fiber-coupled microdisk cavity, we use synchronized amplitude modulation to temporally filter the emitted light. We observe that the single photon purity, temporal overlap between successive emission events, and indistinguishability can be greatly improved with this technique. As this method can be applied to any triggered single photon source, independent of geometry and after device fabrication, it is a flexible approach to improve the performance of solid-state systems, which often suffer from excess dephasing and multi-photon background emission