Quantized Attraction the Disk Around the Star UX Tauri A, in Results Proving the Suppression of Υ States Phys
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research highlights Bottoms down is sequential: the most excited, least force between two parallel metal plates. Phys. Rev. Lett. 109, 222301 (2012) tightly bound 3S state being most greatly This Casimir force could be useful for suppressed, and the 1S state the least, applications in nano-electromechanical as expected. AW systems, but it is not tunable — or at least not in common materials. Wang-Kong Tse On the spot and on the move and Allan H. MacDonald predict that things Nature 491, 426–430 (2012) might be different for the Casimir force Nature 491, 421–425 (2012) between two graphene sheets in a strong magnetic field. A combination of the long-distance transport Tse and MacDonald studied two offered by flying qubits — quantum parallel graphene sheets that are driven information stored in light — and the storage into the quantum Hall regime by a strong capabilities of stationary matter-based qubits perpendicular magnetic field. In this is central to many of the designs for future unusual setting, the Casimir energy quantum-information processors. Two gains an extra contribution from the © ISTOCKPHOTO.COM/CATSCANDOTCOM teams of researchers have now demonstrated Hall current, which results in several how this can be achieved in nanoscale unexpected features. When the sheets are For part of each data-taking year, CERN’s semiconductor devices by entangling a single separated by large distances, the Casimir Large Hadron Collider is given over to spin with a single photon. force becomes quantized; the force can be the acceleration of lead ions, rather than Both Weibo Gao and Kristiaan De Greve either attractive or repulsive depending on protons. These heavy-ion collisions and their respective co-workers investigated the signs of the charge carriers in the two potentially create conditions of such quantum dots that stored a single electron. graphene sheets. Moreover, for charge- extreme temperature and density that the To this they added an optically excited neutral graphene sheets the Casimir force is ion components ‘melt’ into a quark–gluon electron–hole pair, which emitted a photon strongly suppressed. plasma (QGP). Heavy quarks, such as as it relaxed. The researchers demonstrated a These observations, bringing together bottom quarks, that would usually bind quantum correlation between the properties quantum electrodynamics and Hall physics, into quark–antiquark pairs (‘bottomonium’, of this photon and the spin of the electron hint at the possibility of controlling the denoted Υ) in the interaction region left behind. Casimir effect. IG are less likely to do so, their confining Gao and colleagues demonstrated potential screened by the soup of quarks entanglement between spin and photon Dust to dust to dust and gluons. wavelength; De Greve et al., on the other Publ. Natl Astr. Observ. Jpn (in the press); preprint Hence the suppression of bottomonium hand, chose the polarization of the photon. at http://arxiv.org/abs/1206.1215v1 (2012). states is a useful probe of QGP. Through This allowed them to shift the wavelength a comparison of Υ production in of the light from 900 nm to potentially more Planets form within circumstellar, or proton–proton and lead–lead collisions useful telecommunication wavelengths. DG protoplanetary, disks made up of dust and collected in 2011, the CMS collaboration gas left over from the formation of a star. (S. Chatrchyan et al.) have updated their Quantized attraction The disk around the star UX Tauri A, in results proving the suppression of Υ states Phys. Rev. Lett. 109, 236806(2012) the constellation Taurus, might have a gap in heavy-ion collisions, relative to proton separating its inner and outer disks, which is interactions. Moreover, they are now able The presence of boundaries leads to suggestive of planet formation. Ryoko Tanii to resolve three states — Υ(1S), Υ(2S) and measurable manifestations of vacuum and co-workers have used the Subaru Υ(3S) — and show that the suppression fluctuations, such as the attractive Casimir Telescope to image the ‘pre-transitional’ disk at infrared wavelengths. They find unusual polarization data — but no gap. Come together Biophys. J. 103, 2223–2232 (2012) Normally, light scattering from small interstellar dust grains — typically 0.1 μm There is an elegance inherent in the linear-polymer encoding of our genetic information. in size — is strongly polarized regardless of But what happens when distant locations along a single DNA strand need to occupy a the scattering angle. However, in the case single region in space? It turns out that many important cellular processes require such of UX Tauri A, the polarization varies from co-localization, but there is as yet no single plausible physical mechanism for it. 2% to 66%. None of the existing scattering Now, Valentino Bianco and colleagues have shown that the interaction of specific DNA models for protoplanetary disks can explain loci with diffusing molecular species can effectively induce co-localization, via a crossover the measured profile. What does work, characterized by the formation of a single unstable loci pair — the appearance of which however, is a geometric model based on a should be observable in experiment. thin disk of non-spherical dust grains of Bianco et al. designed a pair of schematic models, implicating a general molecular 30-μm diameter. The authors suggest that mechanism for the self-organization of DNA in three dimensions. The two models differ in repeated collisions cause the dust grains to terms of the constraint they place on the valency of molecular species, which determines stick together, forming irregular clumps on a their ability to bridge two or more regions along the polymer. timescale of 105 years. In other words, around When multiple bonds were allowed, Bianco et al. found that DNA loci came together UX Tauri A, a planetary object could be in a single group, whereas the single-valency model engendered a more complex picture, forming right now. MC involving independent sub-groups of loci. A comparison of their results with experimental data revealed scenarios corresponding to both models. AK Written by May Chiao, Iulia Georgescu, David Gevaux, Abigail Klopper and Alison Wright. 4 NATURE PHYSICS | VOL 9 | JANUARY 2013 | www.nature.com/naturephysics © 2013 Macmillan Publishers Limited. All rights reserved.