Physical Review Letters (Phys Rev Lett)

Publications in this journal

• Article: Sequence Controlled Self-Knotting Colloidal Patchy Polymers

  Ivan Coluzza, Peter D. J. van Oostrum, Barbara Capone, Erik Reimhult, Christoph Dellago
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  ABSTRACT: Knotted chains are a promising class of polymers with many applications for materials science and drug delivery. Here we introduce an experimentally realizable model for the design of chains with controllable topological properties. Recently, we have developed a systematic methodology to construct self-assembling chains of simple particles, with final structures fully controlled by the sequence of particles along the chain. The individual particles forming the chain are colloids decorated with mutually interacting patches, which can be manufactured in the laboratory with current technology. Our methodology is applied to the design of sequences folding into self-knotting chains, in which the end monomers are by construction always close together in space. The knotted structure can then be externally locked simply by controlling the interaction between the end monomers, paving the way to applications in the design and synthesis of active materials and novel carriers for drugs delivery.
  Physical Review Letters 10/2013; 110:075501.
• Article: Extension of DNA in a Nanochannel as a Rod-to-Coil Transition

  Douglas R. Tree, Yanwei Wang, Kevin D. Dorfman
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  ABSTRACT: DNA confinement in nanochannels is emerging as an important tool for genomics and an excellent platform for testing the theories of confined wormlike polymers. Using cutting-edge, large scale Monte Carlo simulations of asymptotically long wormlike chains, we show that, in analogy to the rod-to-coil transition for free wormlike polymers, there exists a universal, Gauss–de Gennes regime that connects the classic Odijk and de Gennes regimes of channel-confined chains. For DNA in a nanochannel, this Gauss–de Gennes regime spans practically the entire experimentally relevant range of channel sizes, including the nanochannels used in an incipient genome mapping technology.
  Physical Review Letters 05/2013; 110(20):208103.
• Article: Hydrodynamically Driven Colloidal Assembly in Dip Coating

  C. Colosqui, Jeffrey F. Morris, Howard A. Stone
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  ABSTRACT: We study the hydrodynamics of dip coating from a suspension and report a mechanism for colloidal assembly and pattern formation on smooth substrates. Below a critical withdrawal speed where the coating film is thinner than the particle diameter, capillary forces induced by deformation of the free surface prevent the convective transport of single particles through the meniscus beneath the film. Capillary-induced forces are balanced by hydrodynamic drag only after a minimum number of particles assemble within the meniscus. The particle assembly can thus enter the thin film where it moves at nearly the withdrawal speed and rapidly separates from the next assembly. The interplay between hydrodynamic and capillary forces produces periodic and regular structures below a critical ratio Ca2=3= ffiffiffiffiffiffi Bo p < 0:7, where Ca and Bo are the capillary and Bond numbers, respectively. An analytical model and numerical simulations are presented for the case of two-dimensional flow with circular particles in suspension. The hydrodynamically driven assembly documented here is consistent with stripe pattern formations observed experimentally in dip coating.
  Physical Review Letters 05/2013; 110:188302.
• Article: Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001)

  M. Beye, T. Anniyev, R. Coffee, M. Dell’Angela, A. Fo¨hlisch, J. Gladh, T. Katayama, S. Kaya, O. Krupin, A. Møgelhøj, [......], H. Öberg, H. Ogasawara, L. G. M. Pettersson, W. F. Schlotter, J. A. Sellberg, F. Sorgenfrei, J. J. Turner, M. Wolf, W. Wurth, H. Öström
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  ABSTRACT: We have studied the femtosecond dynamics following optical laser excitation of CO adsorbed on a Ru surface by monitoring changes in the occupied and unoccupied electronic structure using ultrafast soft x-ray absorption and emission. We recently reported [M. Dell’Angela et al. Science 339, 1302 (2013)] a phonon-mediated transition into a weakly adsorbed precursor state occurring on a time scale of >2 ps prior to desorption. Here we focus on processes within the first picosecond after laser excitation and show that the metal-adsorbate coordination is initially increased due to hot-electron-driven vibrational excitations. This process is faster than, but occurs in parallel with, the transition into the precursor state. With resonant x-ray emission spectroscopy, we probe each of these states selectively and determine the respective transient populations depending on optical laser fluence. Ab initio molecular dynamics simulations of CO adsorbed on Ru(0001) were performed at 1500 and 3000 K providing insight into the desorption process.
  Physical Review Letters 05/2013; 110(18):186101.
• Article: Coherent Control of Light Scattering from Nanostructured Materials by Second-Harmonic Generation

  Sergio G Rodrigo, Hayk Harutyunyan, Lukas Novotny
  Physical Review Letters 04/2013; 110(17):177405.
• Article: Generalized Floquet Theory: Application to Dynamical Systems with Memory and Bloch’s Theorem for Nonlocal Potentials

  Fabio L. Traversa, Massimiliano Di Ventra, Fabrizio Bonani
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  ABSTRACT: Floquet theory is a powerful tool in the analysis of many physical phenomena, and extended to spatial coordinates provides the basis for Bloch’s theorem. However, in its original formulation it is limited to linear systems with periodic coefficients. Here, we extend the theory by proving a theorem for the general class of systems including linear operators commuting with the period-shift operator. The present theorem greatly expands the range of applicability of Floquet theory to a multitude of phenomena that were previously inaccessible with this type of analysis, such as dynamical systems with memory. As an important extension, we also prove Bloch’s theorem for nonlocal potentials.
  Physical Review Letters 04/2013; 110:170602.
• Article: Magnetic monopoles and synthetic spin-orbit coupling in Rydberg macrodimers

  Martin Kiffner, Wenhui Li, Dieter Jaksch
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  ABSTRACT: We show that sizeable Abelian and non-Abelian gauge fields arise in the relative motion of two dipole-dipole interacting Rydberg atoms. Our system exhibits two magnetic monopoles for adiabatic motion in one internal two-atom state. These monopoles occur at a characteristic distance between the atoms that is of the order of one micron. The deflection of the relative motion due to the Lorentz force gives rise to a clear signature of the effective magnetic field. In addition, we consider non-adiabatic transitions between two near-degenerate internal states and show that the associated gauge fields are non-Abelian. We present quantum mechanical calculations of this synthetic spin-orbit coupling and show that it realizes a velocity-dependent beamsplitter.
  Physical Review Letters 04/2013; 110:170402.
• Article: Sub-ångstrom Experimental Validation of Molecular Dynamics for Predictive Modeling of Extended Defect Structures in Si

  K. J. Dudeck, L. A. Marqués, A. P. Knights, R. M. Gwilliam, † G. A. Botton
  Physical Review Letters 04/2013; 110(16).
• Article: Optically controlled switching of th echarge state of a single nitrogen-vacan cycenter in diamond at cryogenic temperatures

  P. Siyushev, H. Pinto, M. Vo ̈ro ̈s, A. Gali, F. Jelezko, J. Wrachtrup
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  ABSTRACT: In this Letter, the photoinduced switching of the single nitrogen-vacancy (NV) center between two different charge states, negative (NV-) and neutral (NV0), is studied under resonant excitation at liquid helium temperature. We show that resonant conversion of NV0 to NV- significantly improves spectral stability of the NV- defect and allows high fidelity initialization of the spin qubit. Based on density functional theory calculations a novel mechanism involving an Auger ionization of NV- and charge transfer of an electron from the valence band to NV0 is discussed. This study provides further insight into the charge dynamics of the NV center, which is relevant for quantum information processing based on an NV- defect in diamond.
  Physical Review Letters 04/2013; 110(16):167402.