October 2011 Volume 7, Issue 10

Editorial

Let battle commence p739
doi:10.1038/nphys2126
The final bids are in to host a major radio telescope, the Square Kilometre Array.
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Thesis

Drum roll p741
Mark Buchanan
doi:10.1038/nphys2115
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Book Review

A new kind of science? p742
Reinventing Discovery: The New Era of Networked Science by Michael Nielsen
doi:10.1038/nphys2109
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Research Highlights

Plasma screening | In the loop | Squeezed optics | Shift happens | Calorimetric yo-yo

News and Views

Letters

Experimental investigation of the entanglement-assisted entropic uncertainty principle pp752 - 756
Chuan-Feng Li, Jin-Shi Xu, Xiao-Ye Xu, Ke Li and Guang-Can Guo
doi:10.1038/nphys2047
Heisenberg/'s uncertainty principle limits the precision with which we can measure two complementary properties of a quantum system. Entanglement, it has previously been proposed, can relax these constraints. This idea is now demonstrated experimentally with the aid of polarization-entangled photons.
First paragraph | Full Text | PDF
See also: Letter by Prevedel et al.

Experimental investigation of the uncertainty principle in the presence of quantum memory and its application to witnessing entanglement pp757 - 761
Robert Prevedel, Deny R. Hamel, Roger Colbeck, Kent Fisher and Kevin J. Resch
doi:10.1038/nphys2048
The uncertainty principle tells us that two associated properties of a particle cannot be simultaneously known with infinite precision. However, if the particle is entangled with a quantum memory, the uncertainty of a measurement is reduced. This concept is now observed experimentally.
First paragraph | Full Text | PDF
See also: Letter by Li et al.

Coexistence of magnetic order and two-dimensional superconductivity at LaAlO₃/SrTiO₃ interfaces pp762 - 766
Lu Li, C. Richter, J. Mannhart and R. C. Ashoori
doi:10.1038/nphys2080
Lanthanum aluminate and strontium titanate are insulators, but when you bring them together, the interface between them becomes a two-dimensional superconductor. Even more surprising, magnetometry and transport measurements show that this superconducting state coexists with magnetic order.
First paragraph | Full Text | PDF
See also: News and Views by Millis | Letter by Bert et al.

Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO₃/SrTiO₃ interface pp767 - 771
Julie A. Bert, Beena Kalisky, Christopher Bell, Minu Kim, Yasuyuki Hikita, Harold Y. Hwang and Kathryn A. Moler
doi:10.1038/nphys2079
When the insulators lanthanum aluminate and strontium titanate are brought together, the interface between them forms a two-dimensional superconductor. Moreover, magnetic imaging of this interface shows that superconductivity and ferromagnetism coexist in separated nanoscale domains.
First paragraph | Full Text | PDF
See also: Letter by Li et al. | News and Views by Millis

Topological entanglement entropy of a Bose-Hubbard spin liquid pp772 - 775
Sergei V. Isakov, Matthew B. Hastings and Roger G. Melko
doi:10.1038/nphys2036
Spin liquids are states of matter that reside outside the regime where the Landau paradigm for classifying phases can be applied. This makes them interesting, but also hard to find, as no conventional order parameters exist. The authors demonstrate that topologically ordered spin-liquid phases can be identified by numerically evaluating a measure known as topological entanglement entropy.
First paragraph | Full Text | PDF

Atomically controlled quantum chains hosting a Tomonaga-Luttinger liquid pp776 - 780
C. Blumenstein, J. Schäfer, S. Mietke, S. Meyer, A. Dollinger, M. Lochner, X. Y. Cui, L. Patthey, R. Matzdorf and R. Claessen
doi:10.1038/nphys2051
The Tomonaga-Luttinger liquid model is the leading candidate for describing one-dimensional metallic conductors at low temperature. Yet, experimental evidence that it is valid is sketchy. Scanning tunnelling and photoemission spectra suggest that it does, in fact, describe the behaviour of chains of gold atoms self-assembled on the surface of germanium.
First paragraph | Full Text | PDF
See also: News and Views by Weitering

Extreme-ultraviolet pump-probe studies of one-femtosecond-scale electron dynamics pp781 - 784
P. Tzallas, E. Skantzakis, L. A. A. Nikolopoulos, G. D. Tsakiris and D. Charalambidis
doi:10.1038/nphys2033
Pump-probe measurements are now an essential tool for investigating ultrafast dynamics in atoms and molecules. A lack of sources producing high-intensity attosecond pulses of extreme-ultraviolet (EUV) light has, however, hindered progress. Now, a technique that induces nonlinear processes with EUV light is demonstrated that could circumvent this problem.
First paragraph | Full Text | PDF

Arbitrarily shaped high-coherence electron bunches from cold atoms pp785 - 789
A. J. McCulloch, D. V. Sheludko, S. D. Saliba, S. C. Bell, M. Junker, K. A. Nugent and R. E. Scholten
doi:10.1038/nphys2052
The potential to generate pulsed electron beams with charge distributions tailored in all three dimensions could revolutionize high-speed electron diffraction. A demonstration of a highly coherent pulse electron beam that can be arbitrarily tailored in two dimensions is a step towards this goal.
First paragraph | Full Text | PDF
See also: News and Views by Vredenbregt & Luiten

Articles

A quantum memory intrinsic to single nitrogen-vacancy centres in diamond pp790 - 794
G. D. Fuchs, G. Burkard, P. V. Klimov and D. D. Awschalom
doi:10.1038/nphys2026
A nitrogen impurity in diamond—where two of the carbon atoms are replaced by a nitrogen atom and a vacant lattice site—is seen as a valuable qubit. The spin of an electron localized to the nitrogen-vacancy centre is commonly used for processing. Researchers now show that this electron spin state can be transferred to the nitrogen nuclear spin, where it can be stored until needed.
Abstract | Full Text | PDF

Unconditional room-temperature quantum memory pp795 - 799
M. Hosseini, G. Campbell, B. M. Sparkes, P. K. Lam and B. C. Buchler
doi:10.1038/nphys2021
Optical quantum memories—storage devices for the data encoded in light pulses—will be vital for buffering the flow of quantum information. Researchers now demonstrate such a device that can operate at room temperature. The quantum state is stored in a vapour of rubidium atoms and then recalled with a fidelity in excess of 98%.
Abstract | Full Text | PDF

Quantum spectroscopy with Schrödinger-cat states pp800 - 805
M. Kira, S. W. Koch, R. P. Smith, A. E. Hunter and S. T. Cundiff
doi:10.1038/nphys2091
Experiments that exploit non-classical properties of light promise to provide unique information about many-body systems. The limited availability of non-classical light sources, however, makes their implementation challenging. A method to calculate the quantum-optical response of a material from signals measured by using coherent-light excitation might provide an alternative route.
Abstract | Full Text | PDF
See also: News and Views by Piermarocchi

Nodal quasiparticle meltdown in ultrahigh-resolution pump-probe angle-resolved photoemission pp806 - 810
J. Graf, C. Jozwiak, C. L. Smallwood, H. Eisaki, R. A. Kaindl, D-H. Lee and A. Lanzara
doi:10.1038/nphys2027
Where a superconductor has a node, or a zero, in the superconducting gap, low-energy excitations exist that are similar to those in normal metals and are thought to be unaffected by superconductivity. However, excitation of superconductors with a near infrared pulse reveals there is a link between these excitations and superconductivity.
Abstract | Full Text | PDF

Aharonov-Bohm interferences from local deformations in graphene pp811 - 816
Fernando de Juan, Alberto Cortijo, María A. H. Vozmediano and Andrés Cano
doi:10.1038/nphys2034
Mechanical deformations in graphene have been shown to be associated with 'fictitious' magnetic fields. Theoretical work now suggests that these fields can give rise to an analogue of the Aharonov-Bohm effect, a phenomenon that might be used to sensitively detect small deformations of the graphene sheet.
Abstract | Full Text | PDF

Predicting the density-scaling exponent of a glass-forming liquid from Prigogine-Defay ratio measurements pp817 - 822
Ditte Gundermann, Ulf R. Pedersen, Tina Hecksher, Nicholas P. Bailey, Bo Jakobsen, Tage Christensen, Niels B. Olsen, Thomas B. Schrøder, Daniel Fragiadakis, Riccardo Casalini, C. Michael Roland, Jeppe C. Dyre and Kristine Niss
doi:10.1038/nphys2031
The Prigogine-Defay ratio quantifies how many parameters are needed to fully characterize the glass-transition behaviour of a viscous liquid. For a single parameter, this ratio is unity, but it has never been clear whether any real liquid has such a value. A discovery of a connection between this ratio and the density scaling behaviour of silicone oil suggests it does.
Abstract | Full Text | PDF
See also: News and Views by Angell & Klein

Generalized molecular orbital tomography pp823 - 827
C. Vozzi, M. Negro, F. Calegari, G. Sansone, M. Nisoli, S. De Silvestri and S. Stagira
doi:10.1038/nphys2029
Atomic and molecular gases generate extreme ultraviolet light when excited by pulses of intense laser light. This emission provides information about the inner workings of the molecules and even enables us to map electron orbitals. However, so far molecular orbital tomography has been restricted to simple molecules. A technique that can be applied to more complicated molecules is now unveiled.
Abstract | Full Text | PDF