- Computational Model for Cell Morphodynamics
Author(s): Danying Shao, Wouter-Jan Rappel, and Herbert Levine
We develop a computational model, based on the phase-field method, for cell morphodynamics and apply it to fish keratocytes. Our model incorporates the membrane bending force and the surface tension and enforces a constant area. Furthermore, it implements a cross-linked actin filament field and an a...
[Phys. Rev. Lett. 105, 108104] Published Thu Sep 02, 2010
- Pulsed Nuclear Pumping and Spin Diffusion in a Single Charged Quantum Dot
Author(s): Thaddeus D. Ladd, David Press, Kristiaan De Greve, Peter L. McMahon, Benedikt Friess, Christian Schneider, Martin Kamp, Sven Höfling, Alfred Forchel, and Yoshihisa Yamamoto
We report the observation of a feedback process between the nuclear spins in a single charged quantum dot under coherently pulsed optical excitation and its trion transition. The optical pulse sequence intersperses resonant narrow-band pumping for spin initialization with off-resonant ultrafast puls...
[Phys. Rev. Lett. 105, 107401] Published Thu Sep 02, 2010
- Unified Picture for Magnetic Correlations in Iron-Based Superconductors
Author(s): Wei-Guo Yin, Chi-Cheng Lee, and Wei Ku
The varying metallic antiferromagnetic correlations observed in iron-based superconductors are unified in a model consisting of both itinerant electrons and localized spins. The decisive factor is found to be the sensitive competition between the superexchange antiferromagnetism and the orbital-dege...
[Phys. Rev. Lett. 105, 107004] Published Thu Sep 02, 2010
- Unconventional Superconductivity and Antiferromagnetic Quantum Critical Behavior in the Isovalent-Doped BaFe_{2} (As_{1-x} P_{x} )_{2}
Author(s): Y. Nakai, T. Iye, S. Kitagawa, K. Ishida, H. Ikeda, S. Kasahara, H. Shishido, T. Shibauchi, Y. Matsuda, and T. Terashima
Spin dynamics evolution of BaFe_{2} (As_{1-x} P_{x} )_{2} was probed as a function of P concentration via ^{31} P NMR. Our NMR study reveals that two-dimensional antiferromagnetic (AF) fluctuations are notably enhanced with little change in static susceptibility on approaching the AF phase from the ...
[Phys. Rev. Lett. 105, 107003] Published Thu Sep 02, 2010
- Atom-Dimer Scattering in a Three-Component Fermi Gas
Author(s): T. Lompe, T. B. Ottenstein, F. Serwane, K. Viering, A. N. Wenz, G. Zürn, and S. Jochim
Ultracold gases of three distinguishable particles with large scattering lengths are expected to show rich few-body physics related to the Efimov effect. We have created three different mixtures of ultracold ^{6} Li atoms and weakly bound ^{6} Li _{2} dimers consisting of atoms in three different hy...
[Phys. Rev. Lett. 105, 103201] Published Thu Sep 02, 2010
- Constraining the Noncommutative Spectral Action via Astrophysical Observations
Author(s): William Nelson, Joseph Ochoa, and Mairi Sakellariadou
The noncommutative spectral action extends our familiar notion of commutative spaces, using the data encoded in a spectral triple on an almost commutative space. Varying a rather simple action, one can derive all of the standard model of particle physics in this setting, in addition to a modified ve...
[Phys. Rev. Lett. 105, 101602] Published Thu Sep 02, 2010
- Probing Quark-Gluon Interactions with Transverse Polarized Scattering
Author(s): K. Slifer et al. (Resonance Spin Structure Collaboration)
We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d_{2} [over ˜] , which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence ...
[Phys. Rev. Lett. 105, 101601] Published Thu Sep 02, 2010
- Black Strings, Low Viscosity Fluids, and Violation of Cosmic Censorship
Author(s): Luis Lehner and Frans Pretorius
We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black ...
[Phys. Rev. Lett. 105, 101102] Published Thu Sep 02, 2010
- Four-Qubit Entanglement Classification from String Theory
Author(s): L. Borsten, D. Dahanayake, M. J. Duff, A. Marrani, and W. Rubens
We invoke the black-hole–qubit correspondence to derive the classification of four-qubit entanglement. The U-duality orbits resulting from timelike reduction of string theory from D=4 to D=3 yield 31 entanglement families, which reduce to nine up to permutation of the four qubits.
[Phys. Rev. Lett. 105, 100507] Published Thu Sep 02, 2010
- Qubit State Monitoring by Measurement of Three Complementary Observables
Author(s): Rusko Ruskov, Alexander N. Korotkov, and Klaus Mølmer
We consider the evolution of a qubit (spin 1/2) under the simultaneous continuous measurement of three noncommuting qubit operators σ [over ^] _{x} , σ [over ^] _{y} , and σ [over ^] _{z} . For identical ideal detectors, the qubit state evolves by approaching a pure state with a random direction ...
[Phys. Rev. Lett. 105, 100506] Published Thu Sep 02, 2010
- Response of the Strongly Driven Jaynes-Cummings Oscillator
Author(s): Lev S. Bishop, Eran Ginossar, and S. M. Girvin
We analyze the Jaynes-Cummings model of quantum optics, in the strong-dispersive regime. In the bad-cavity limit and on time scales short compared to the atomic coherence time, the dynamics are those of a nonlinear oscillator. A steady-state nonperturbative semiclassical analysis exhibits a finite r...
[Phys. Rev. Lett. 105, 100505] Published Thu Sep 02, 2010
- Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities
Author(s): Maxime Boissonneault, J. M. Gambetta, and Alexandre Blais
In dispersive readout schemes, qubit-induced nonlinearity typically limits the measurement fidelity by reducing the signal-to-noise ratio (SNR) when the measurement power is increased. Contrary to seeing the nonlinearity as a problem, here we propose to use it to our advantage in a regime where it c...
[Phys. Rev. Lett. 105, 100504] Published Thu Sep 02, 2010
- Interplay between Charge Order, Ferroelectricity, and Ferroelasticity: Tungsten Bronze Structures as a Playground for Multiferroicity
Author(s): Kunihiko Yamauchi and Silvia Picozzi
Charge order is proposed as a driving force behind ferroelectricity in iron fluoride K_{0.6} Fe_{0.6}^{II} Fe_{0.4}^{III} F_{3} . By means of density functional theory, we propose several noncentrosymmetric d^{5} /d^{6} charge-ordering patterns, each giving rise to polarization with different direct...
[Phys. Rev. Lett. 105, 107202] Published Wed Sep 01, 2010
- Zero Landau Level in Folded Graphene Nanoribbons
Author(s): E. Prada, P. San-Jose, and L. Brey
Graphene nanoribbons can be folded into a double layer system keeping the two layers decoupled. In the quantum Hall regime folds behave as a new type of Hall bar edge. We show that the symmetry properties of the zero Landau level in metallic nanoribbons dictate that the zero energy edge states trave...
[Phys. Rev. Lett. 105, 106802] Published Wed Sep 01, 2010
- Apparent Power-Law Behavior of Conductance in Disordered Quasi-One-Dimensional Systems
Author(s): A. S. Rodin and M. M. Fogler
The dependence of hopping conductance on temperature and voltage for an ensemble of modestly long one-dimensional wires is studied numerically using the shortest-path algorithm. In a wide range of parameters this dependence can be approximated by a power law rather than the usual stretched-exponenti...
[Phys. Rev. Lett. 105, 106801] Published Wed Sep 01, 2010
- Unconventional T-H Phase Diagram in the Noncentrosymmetric Compound Yb_{2} Fe_{12} P_{7}
Author(s): R. E. Baumbach, J. J. Hamlin, L. Shu, D. A. Zocco, J. R. O’Brien, P.-C. Ho, and M. B. Maple
The temperature–(T-)magnetic-field (H) phase diagram for the noncentrosymmetric compound Yb_{2} Fe_{12} P_{7} , determined from electrical resistivity (ρ), specific heat (C), and magnetization (M) measurements on single crystal specimens, is reported. This system exhibits a crossover from a magne...
[Phys. Rev. Lett. 105, 106403] Published Wed Sep 01, 2010
- Edge-Mediated Dislocation Processes in Multishell Carbon Nano-Onions?
Author(s): E. Akatyeva, J. Y. Huang, and T. Dumitrică
We report in situ electron microscopy observations of dislocation dissociation and annihilation processes in individual nanometer-sized carbon onions. Essential for these processes is the counterintuitive motion of the 1/2⟨0001⟩ edge from the outer surface to the inner region, which cross-links...
[Phys. Rev. Lett. 105, 106102] Published Wed Sep 01, 2010
- Bending Crystals: Emergence of Fractal Dislocation Structures
Author(s): Yong S. Chen, Woosong Choi, Stefanos Papanikolaou, and James P. Sethna
We provide a minimal continuum model for mesoscale plasticity, explaining the cellular dislocation structures observed in deformed crystals. Our dislocation density tensor evolves from random, smooth initial conditions to form self-similar structures strikingly similar to those seen experimentallyâ€...
[Phys. Rev. Lett. 105, 105501] Published Wed Sep 01, 2010
- Self-Guided Laser Wakefield Acceleration beyond 1 GeV Using Ionization-Induced Injection
Author(s): C. E. Clayton, J. E. Ralph, F. Albert, R. A. Fonseca, S. H. Glenzer, C. Joshi, W. Lu, K. A. Marsh, S. F. Martins, W. B. Mori, A. Pak, F. S. Tsung, B. B. Pollock, J. S. Ross, L. O. Silva, and D. H. Froula
The concepts of matched-beam, self-guided laser propagation and ionization-induced injection have been combined to accelerate electrons up to 1.45Â GeV energy in a laser wakefield accelerator. From the spatial and spectral content of the laser light exiting the plasma, we infer that the 60Â fs, 110Â...
[Phys. Rev. Lett. 105, 105003] Published Wed Sep 01, 2010
- High-Harmonic Homodyne Detection of the Ultrafast Dissociation of Br_{2} Molecules
Author(s): H. J. Wörner, J. B. Bertrand, P. B. Corkum, and D. M. Villeneuve
We report the time-resolved observation of the photodissociation of Br_{2} using high-harmonic generation (HHG) as a probe. The simultaneous measurement of the high-harmonic and ion yields shows that high harmonics generated by the electronically excited state interfere with harmonics generated by t...
[Phys. Rev. Lett. 105, 103002] Published Wed Sep 01, 2010
- Prolate-Spherical Shape Coexistence at N=28 in ^{44} S
Author(s): C. Force, S. Grévy, L. Gaudefroy, O. Sorlin, L. Cáceres, F. Rotaru, J. Mrazek, N. L. Achouri, J. C. Angélique, F. Azaiez, B. Bastin, R. Borcea, A. Buta, J. M. Daugas, Z. Dlouhy, Zs. Dombrádi, F. De Oliveira, F. Negoita, Y. Penionzhkevich, M. G. Saint-Laurent, D. Sohler, M. Stanoiu, I. Stefan, C. Stodel, and F. Nowacki
The structure of ^{44} S has been studied by using delayed γ and electron spectroscopy. The decay rates of the 0_{2}^{+} isomeric state to the 2_{1}^{+} and 0_{1}^{+} states, measured for the first time, lead to a reduced transition probability B(E2: 2_{1}^{+} →0_{2}^{+} )=8.4(26) e^{2}...
[Phys. Rev. Lett. 105, 102501] Published Wed Sep 01, 2010
- Thermalization in a Coherently Driven Ensemble of Two-Level Systems
Author(s): Igor Lesanovsky, Beatriz Olmos, and Juan P. Garrahan
We investigate the coherent quantum time evolution of a driven mesoscopic chain of two-level systems that interact via the van der Waals interaction in their excited state. The Hamiltonian is the sum of a classical lattice gas Hamiltonian and an off-diagonal driving term without classical counterp...
[Phys. Rev. Lett. 105, 100603] Published Wed Sep 01, 2010
- Origin of Hyperdiffusion in Generalized Brownian Motion
Author(s): P. Siegle, I. Goychuk, and P. Hänggi
We study a minimal non-Markovian model of superdiffusion which originates from long-range velocity correlations within the generalized Langevin equation approach. The model allows for a three-dimensional Markovian embedding. The emergence of a transient hyperdiffusion, ⟨Δx^{2} (t)⟩∝t^{2+λ} ,...
[Phys. Rev. Lett. 105, 100602] Published Wed Sep 01, 2010
- Role of Initial Entanglement and Non-Gaussianity in the Decoherence of Photon-Number Entangled States Evolving in a Noisy Channel
Author(s): Michele Allegra, Paolo Giorda, and Matteo G. A. Paris
We address the degradation of continuous variable (CV) entanglement in a noisy channel focusing on the set of photon-number entangled states. We exploit several separability criteria and compare the resulting separation times with the value of non-Gaussianity at any time, thus showing that in the lo...
[Phys. Rev. Lett. 105, 100503] Published Wed Sep 01, 2010
- High-Coherence Hybrid Superconducting Qubit
Author(s): Matthias Steffen, Shwetank Kumar, David P. DiVincenzo, J. R. Rozen, George A. Keefe, Mary Beth Rothwell, and Mark B. Ketchen
We report quantum coherence measurements of a superconducting qubit whose design is a hybrid of several existing types. Excellent coherence times are found: T_{2}^{*} ∼T_{1} ∼1.5 μs. The topology of the qubit is that of a traditional three-junction flux qubit, but it has a large shunting c...
[Phys. Rev. Lett. 105, 100502] Published Wed Sep 01, 2010
- Nanometer Axial Resolution by Three-Dimensional Supercritical Angle Fluorescence Microscopy
Author(s): Christian M. Winterflood, Thomas Ruckstuhl, Dorinel Verdes, and Stefan Seeger
We report a noninvasive fluorescence microscopy method and demonstrate nanometer resolution along the optical axis. The technique is based on the influence of the microscope slide on the angular intensity distribution of fluorescence. Axial positions are determined by measuring the proportion of lig...
[Phys. Rev. Lett. 105, 108103] Published Tue Aug 31, 2010
- Simplified Exactly Solvable Model for β-Amyloid Aggregation
Author(s): M. Zamparo, A. Trovato, and A. Maritan
We propose an exactly solvable simplified statistical mechanical model for the thermodynamics of β-amyloid aggregation, generalizing a well-studied model for protein folding. The monomer concentration is explicitly taken into account as well as a nontrivial dependence on the microscopic degrees of ...
[Phys. Rev. Lett. 105, 108102] Published Tue Aug 31, 2010
- Chiral Symmetry Breaking in Crystals of Achiral Polymers
Author(s): Yashodhan Hatwalne and M. Muthukumar
Many achiral polymers crystallize into spherulites with gigantic chirality, as is evident from spectacular images of periodic banding observed in a polarized optical microscope, arising from the twisting of the lamellae making up the spherulites. We present a new mechanism of the spontaneous chiral ...
[Phys. Rev. Lett. 105, 107801] Published Tue Aug 31, 2010
- Magnetization Patterns in Ferromagnetic Nanoelements as Functions of Complex Variable
Author(s): Konstantin L. Metlov
The assumption of a certain hierarchy of soft ferromagnet energy terms, realized in small enough flat nanoelements, allows us to obtain explicit expressions for their magnetization distributions. By minimizing the energy terms sequentially, from the most to the least important, magnetization distrib...
[Phys. Rev. Lett. 105, 107201] Published Tue Aug 31, 2010
- Nonlocal Cooper Pair Splitting in a pSn Junction
Author(s): M. Veldhorst and A. Brinkman
Perfect Cooper pair splitting is proposed, based on crossed Andreev reflection (CAR) in a p-type semiconductor-superconductor-n-type semiconductor (pSn) junction. The ideal splitting is caused by the energy filtering that is enforced by the band structure of the electrodes. The pSn junction is model...
[Phys. Rev. Lett. 105, 107002] Published Tue Aug 31, 2010
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