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  • 1
    Publication Date: 2011-12-24
    Description: Interaction blockade occurs when strong interactions in a confined, few-body system prevent a particle from occupying an otherwise accessible quantum state. Blockade phenomena reveal the underlying granular nature of quantum systems and allow for the detection and manipulation of the constituent particles, be they electrons, spins, atoms or photons. Applications include single-electron transistors based on electronic Coulomb blockade and quantum logic gates in Rydberg atoms. Here we report a form of interaction blockade that occurs when transferring ultracold atoms between orbitals in an optical lattice. We call this orbital excitation blockade (OEB). In this system, atoms at the same lattice site undergo coherent collisions described by a contact interaction whose strength depends strongly on the orbital wavefunctions of the atoms. We induce coherent orbital excitations by modulating the lattice depth, and observe staircase-like excitation behaviour as we cross the interaction-split resonances by tuning the modulation frequency. As an application of OEB, we demonstrate algorithmic cooling of quantum gases: a sequence of reversible OEB-based quantum operations isolates the entropy in one part of the system and then an irreversible step removes the entropy from the gas. This technique may make it possible to cool quantum gases to have the ultralow entropies required for quantum simulation of strongly correlated electron systems. In addition, the close analogy between OEB and dipole blockade in Rydberg atoms provides a plan for the implementation of two-quantum-bit gates in a quantum computing architecture with natural scalability.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bakr, Waseem S -- Preiss, Philipp M -- Tai, M Eric -- Ma, Ruichao -- Simon, Jonathan -- Greiner, Markus -- England -- Nature. 2011 Dec 21;480(7378):500-3. doi: 10.1038/nature10668.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22193104" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2011-04-15
    Description: Understanding exotic forms of magnetism in quantum mechanical systems is a central goal of modern condensed matter physics, with implications for systems ranging from high-temperature superconductors to spintronic devices. Simulating magnetic materials in the vicinity of a quantum phase transition is computationally intractable on classical computers, owing to the extreme complexity arising from quantum entanglement between the constituent magnetic spins. Here we use a degenerate Bose gas of rubidium atoms confined in an optical lattice to simulate a chain of interacting quantum Ising spins as they undergo a phase transition. Strong spin interactions are achieved through a site-occupation to pseudo-spin mapping. As we vary a magnetic field, quantum fluctuations drive a phase transition from a paramagnetic phase into an antiferromagnetic phase. In the paramagnetic phase, the interaction between the spins is overwhelmed by the applied field, which aligns the spins. In the antiferromagnetic phase, the interaction dominates and produces staggered magnetic ordering. Magnetic domain formation is observed through both in situ site-resolved imaging and noise correlation measurements. By demonstrating a route to quantum magnetism in an optical lattice, this work should facilitate further investigations of magnetic models using ultracold atoms, thereby improving our understanding of real magnetic materials.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Simon, Jonathan -- Bakr, Waseem S -- Ma, Ruichao -- Tai, M Eric -- Preiss, Philipp M -- Greiner, Markus -- England -- Nature. 2011 Apr 21;472(7343):307-12. doi: 10.1038/nature09994. Epub 2011 Apr 13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21490600" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2013-11-12
    Description: In multicellular organisms, transcription regulation is one of the central mechanisms modelling lineage differentiation and cell-fate determination. Transcription requires dynamic chromatin configurations between promoters and their corresponding distal regulatory elements. It is believed that their communication occurs within large discrete foci of aggregated RNA polymerases termed transcription factories in three-dimensional nuclear space. However, the dynamic nature of chromatin connectivity has not been characterized at the genome-wide level. Here, through a chromatin interaction analysis with paired-end tagging approach using an antibody that primarily recognizes the pre-initiation complexes of RNA polymerase II, we explore the transcriptional interactomes of three mouse cells of progressive lineage commitment, including pluripotent embryonic stem cells, neural stem cells and neurosphere stem/progenitor cells. Our global chromatin connectivity maps reveal approximately 40,000 long-range interactions, suggest precise enhancer-promoter associations and delineate cell-type-specific chromatin structures. Analysis of the complex regulatory repertoire shows that there are extensive colocalizations among promoters and distal-acting enhancers. Most of the enhancers associate with promoters located beyond their nearest active genes, indicating that the linear juxtaposition is not the only guiding principle driving enhancer target selection. Although promoter-enhancer interactions exhibit high cell-type specificity, promoters involved in interactions are found to be generally common and mostly active among different cells. Chromatin connectivity networks reveal that the pivotal genes of reprogramming functions are transcribed within physical proximity to each other in embryonic stem cells, linking chromatin architecture to coordinated gene expression. Our study sets the stage for the full-scale dissection of spatial and temporal genome structures and their roles in orchestrating development.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3954713/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3954713/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, Yubo -- Wong, Chee-Hong -- Birnbaum, Ramon Y -- Li, Guoliang -- Favaro, Rebecca -- Ngan, Chew Yee -- Lim, Joanne -- Tai, Eunice -- Poh, Huay Mei -- Wong, Eleanor -- Mulawadi, Fabianus Hendriyan -- Sung, Wing-Kin -- Nicolis, Silvia -- Ahituv, Nadav -- Ruan, Yijun -- Wei, Chia-Lin -- 1U54HG004557-01/HG/NHGRI NIH HHS/ -- GGP12152/Telethon/Italy -- GM61390/GM/NIGMS NIH HHS/ -- R01 DK090382/DK/NIDDK NIH HHS/ -- R01 HD059862/HD/NICHD NIH HHS/ -- R01 HG004456-01/HG/NHGRI NIH HHS/ -- R01 NS079231/NS/NINDS NIH HHS/ -- R01DK090382/DK/NIDDK NIH HHS/ -- R01HD059862/HD/NICHD NIH HHS/ -- R01HG003521-01/HG/NHGRI NIH HHS/ -- R01HG005058/HG/NHGRI NIH HHS/ -- R01HG006768/HG/NHGRI NIH HHS/ -- R01NS079231/NS/NINDS NIH HHS/ -- U01 GM061390/GM/NIGMS NIH HHS/ -- U19 GM061390/GM/NIGMS NIH HHS/ -- England -- Nature. 2013 Dec 12;504(7479):306-10. doi: 10.1038/nature12716. Epub 2013 Nov 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Sequencing Technology Group, Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, California 94598, USA [2] [3] Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel (R.Y.B.); National Heart, Lung, and Blood Institute, National Institutes of Health, Systems Biology Center, 9000 Rockville Pike, Bethesda, Maryland 20892, USA (Y.Z.). ; 1] Sequencing Technology Group, Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, California 94598, USA [2]. ; 1] Department of Bioengineering and Therapeutic Sciences, Institute for Human Genetics, UCSF, San Francisco, California 94158, USA [2] [3] Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel (R.Y.B.); National Heart, Lung, and Blood Institute, National Institutes of Health, Systems Biology Center, 9000 Rockville Pike, Bethesda, Maryland 20892, USA (Y.Z.). ; 1] The Jackson Laboratory for Genomic Medicine, and Department of Genetic and Development Biology, University of Connecticut, 400 Farmington, Connecticut 06030, USA [2] Genome Institute of Singapore, 60 Biopolis Street, 138672 Singapore. ; Department of Biological Sciences and Biotechnology, University of Milano-Bicocca, 20126 Milano, Italy. ; Sequencing Technology Group, Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, California 94598, USA. ; Genome Institute of Singapore, 60 Biopolis Street, 138672 Singapore. ; Department of Bioengineering and Therapeutic Sciences, Institute for Human Genetics, UCSF, San Francisco, California 94158, USA. ; The Jackson Laboratory for Genomic Medicine, and Department of Genetic and Development Biology, University of Connecticut, 400 Farmington, Connecticut 06030, USA. ; 1] Sequencing Technology Group, Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek, California 94598, USA [2] Genome Institute of Singapore, 60 Biopolis Street, 138672 Singapore.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24213634" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; Cell Lineage ; Chromatin/*genetics/*metabolism ; Embryonic Stem Cells/metabolism ; Enhancer Elements, Genetic/*genetics ; Gene Expression Regulation/*genetics ; In Situ Hybridization, Fluorescence ; Mice ; Neural Stem Cells/metabolism ; Promoter Regions, Genetic/*genetics ; RNA Polymerase II/metabolism ; Transcription, Genetic/genetics ; Zebrafish/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2015-12-04
    Description: Entanglement is one of the most intriguing features of quantum mechanics. It describes non-local correlations between quantum objects, and is at the heart of quantum information sciences. Entanglement is now being studied in diverse fields ranging from condensed matter to quantum gravity. However, measuring entanglement remains a challenge. This is especially so in systems of interacting delocalized particles, for which a direct experimental measurement of spatial entanglement has been elusive. Here, we measure entanglement in such a system of itinerant particles using quantum interference of many-body twins. Making use of our single-site-resolved control of ultracold bosonic atoms in optical lattices, we prepare two identical copies of a many-body state and interfere them. This enables us to directly measure quantum purity, Renyi entanglement entropy, and mutual information. These experiments pave the way for using entanglement to characterize quantum phases and dynamics of strongly correlated many-body systems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Islam, Rajibul -- Ma, Ruichao -- Preiss, Philipp M -- Tai, M Eric -- Lukin, Alexander -- Rispoli, Matthew -- Greiner, Markus -- England -- Nature. 2015 Dec 3;528(7580):77-83. doi: 10.1038/nature15750.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26632587" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2015-03-15
    Description: Full control over the dynamics of interacting, indistinguishable quantum particles is an important prerequisite for the experimental study of strongly correlated quantum matter and the implementation of high-fidelity quantum information processing. We demonstrate such control over the quantum walk-the quantum mechanical analog of the classical random walk-in the regime where dynamics are dominated by interparticle interactions. Using interacting bosonic atoms in an optical lattice, we directly observed fundamental effects such as the emergence of correlations in two-particle quantum walks, as well as strongly correlated Bloch oscillations in tilted optical lattices. Our approach can be scaled to larger systems, greatly extending the class of problems accessible via quantum walks.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Preiss, Philipp M -- Ma, Ruichao -- Tai, M Eric -- Lukin, Alexander -- Rispoli, Matthew -- Zupancic, Philip -- Lahini, Yoav -- Islam, Rajibul -- Greiner, Markus -- New York, N.Y. -- Science. 2015 Mar 13;347(6227):1229-33. doi: 10.1126/science.1260364.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, Harvard University, Cambridge, MA 02138, USA. ; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. ; Department of Physics, Harvard University, Cambridge, MA 02138, USA. greiner@physics.harvard.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25766229" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    ISSN: 1573-9120
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The parameters of free oscillations in gyrotron resonators with a lowered reflection from the diffractive energy output for the purpose of reducing ohmic heating by rf power loss have been calculated. A gyrotron with such a cavity has been studied experimentally. The gyrotron had an efficiency of more than 45% with an output of 350 to 700 kW when operating in the 3.6-mm H11,3 mode.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunological studies of forty-three patients with cystic fibrosis showed that positive prick tests to at least one common allergen were obtained in 70%, to multiple allergens in 28% and to A. fumigatus in 50%. Specific IgE antibodies against these allergens were found in the appropriate subjects. In spite of this evidence of type 1, IgE, sen-sitization none of the patients had a history of infantile eczema.Intracutaneous tests with A. fumigatus extract gave types 1 and 3 reactions in sixteen patients (37%), only seven of whom were among the sixteen (37%) who gave positive precipitin tests.Raised levels of total serum IgG and IgA were found as compared with healthy controls and asthmatic subjects. No differences were found in total serum IgM and IgD levels.The high incidence of allergy to A. fumigatus in cystic fibrosis is confirmed.
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  • 8
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A double-blind statistically controlled study was carried out on ninety-six patients with Type I allergy to D. pteronyssinus and a history of perennial asthma and/or rhinitis. Forty-eight received injections of an extract of Dermatophagoides pteronyssinus and forty-eight controls received injections of carbol saline. Both groups were closely comparable in all respects. Ninety-one were available for assessment, forty-six controls, and forty-five treated.The D. pteronyssinus treated group showed a statistically significant decrease in nasal sensitivity to the mite extract after treatment and recorded less asthma, less use of drugs and an increased clinical tolerance of household dust.A significant rise in specific IgE to D. pteronyssinus was found in twenty-three out of forty (58%) of the treated compared with eight out of forty-one (20%) of the controls and a rise in total IgE in twenty out of forty (50%) of the treated compared with nine out of thirty-nine (23%) of the control group.Specific IgG antibodies to D. pteronyssinus were found prior to treatment in twelve out of thirty-nine (30%) of controls and twelve out of forty (31%) of the treated group. There was a significant increase in the number of patients with specific IgG antibody after injections of D. pteronyssinus extract as compared with the controls. This increase was associated with clinical improvement which occurred mainly in subjects who showed a decrease, little change or an increase of less than 30% in specific IgE antibody. In those with an increase of more than 30% in specific IgE antibody there was no evidence of clinical improvement even if specific IgG was produced.Diminished release of histamine from leucocytes was found after treatment in six out of ten treated compared with three out of eleven controls. There were, however, no differences between treatment and control groups in lymphocyte transformation and the liberation of leucocyte inhibitory agents.Clinical improvement was significantly better in those treated patients who gave strong nasal and skin reactions before treatment than in those with weak nasal and skin reactivity, who were no different from the controls.
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