Physical Review Letters

Julien, Keith ; Knobloch, Edgar ; Rubio, Antonio M; Vasil, Geoffrey M

doi: 10.1103/PhysRevLett.109.254503pmid: 23368470

We demonstrate, via simulations of asymptotically reduced equations describing rotationally constrained Rayleigh-Bénard convection, that the efficiency of turbulent motion in the fluid bulk limits overall heat transport and determines the scaling of the nondimensional Nusselt number Nu with the Rayleigh number Ra , the Ekman number E , and the Prandtl number σ . For E ≪ 1 inviscid scaling theory predicts and simulations confirm the large Ra scaling law Nu - 1 ≈ C 1 σ - 1 / 2 R a 3 / 2 E 2 , where C 1 is a constant, estimated as <?format ?> C 1 ≈ 0.04 ± 0.0025 . In contrast, the corresponding result for nonrotating convection, Nu - 1 ≈ C 2 R a α , is determined by the efficiency of the thermal boundary layers (laminar: 0.28 ≲ α ≲ 0.31 , turbulent: α ∼ 0.38 ). The 3 / 2 scaling law breaks down at Rayleigh numbers at which the thermal boundary layer loses rotational constraint, i.e., when the local Rossby number ≈ 1 . The breakdown takes place while the bulk Rossby number is still small and results in a gradual transition to the nonrotating scaling law. For low Ekman numbers the location of this transition is independent of the mechanical boundary conditions.

Pani, Paolo ; Sotiriou, Thomas P

doi: 10.1103/PhysRevLett.109.251102pmid: 23368444

Eddington-inspired Born-Infeld gravity was recently proposed as an alternative to general relativity that offers a resolution of spacetime singularities. The theory differs from Einstein’s gravity only inside matter due to nondynamical degrees of freedom, and it is compatible with all current observations. We show that the theory is reminiscent of Palatini f ( R ) gravity and that it shares the same pathologies, such as curvature singularities at the surface of polytropic stars and unacceptable Newtonian limit. This casts serious doubt on its viability.

Smolka, S; Huck, A; Andersen, U. L; Lagendijk, A. L; Lodahl, P. L

doi: 10.1103/PhysRevLett.109.259904pmid: N/A

Schwabe, Andrej ; Gütersloh, Daniel ; Potthoff, Michael

doi: 10.1103/PhysRevLett.109.257202pmid: 23368491

Nanoscale systems of metal atoms antiferromagnetically exchange coupled to several magnetic impurities are shown to exhibit an unconventional reentrant competition between Kondo screening and indirect magnetic exchange interaction. Depending on the atomic positions of the magnetic moments, the total ground-state spin deviates from predictions of standard Ruderman-Kittel-Kasuya-Yosida perturbation theory. The effect shows up on an energy scale larger than the level width induced by the coupling to the environment and is experimentally accessible by studying magnetic field dependencies.

Yoon, Jae Woong; Koh, Gang Min; Song, Seok Ho; Magnusson, Robert Ho

doi: 10.1103/PhysRevLett.109.257402pmid: 23368498

We demonstrate the plasmonic analogue of a coherent photonic effect known as coherent perfect absorption. A periodically nanopatterned metal film perfectly absorbs multiple coherent light beams coupling to a single surface plasmon mode. The perfect absorbing state can be switched to a nearly perfect scattering state by tuning the phase difference between the incident beams. We theoretically explain the plasmonic coherent perfect absorption by considering time-reversal symmetry of surface plasmon amplification by stimulated emission of radiation. We experimentally demonstrate coherent control of the plasmonic absorption in good agreement with a coupled-mode theory of dissipative resonances. Associated potential applications include absorption-based plasmonic switches, modulators, and light-electricity transducers.

Bihr, Timo ; Seifert, Udo ; Smith, Ana-Sunčana

doi: 10.1103/PhysRevLett.109.258101pmid: 23368503

We present a comprehensive model for the nucleation of domains in membrane adhesion. We determine the critical number of bonds in a nucleus and calculate the probability distribution of nucleation time from a discrete master equation. The latter is characterized by only four effective rates, which account for cooperative effects between bonds. We validate our model by finding excellent agreement with extensive Langevin simulations. In the range of parameters typical for cell adhesion, we find the critical number of bonds to be small. Furthermore, we find a characteristic separation between the bonds at which nucleation is particularly fast, pointing to potential regulatory mechanisms that could be used to control the cell recognition processes.

Araki, Takeaki

doi: 10.1103/PhysRevLett.109.257801pmid: 23368501

When a nematic liquid crystal is confined in a porous medium with strong anchoring conditions, topological defects, called disclinations, are stably formed with numerous possible configurations. Since the energy barriers between them are large enough, the system shows multistability. Our lattice Boltzmann simulations demonstrate dynamic couplings between the multistable defect pattern and the flow in a regular porous matrix. At sufficiently low flow speed, the topological defects are pinned at the quiescent positions. As the flow speed is increased, the defects show cyclic motions and nonlinear rheological properties, which depend on whether or not they are topologically constrained in the porous networks. In addition, we discover that the defect pattern can be controlled by controlling the flow. Thus, the flow path is recorded in the porous channels owing to the multistability of the defect patterns.

Abelev, B; Adam, J; Adamová, D; Adare, A. M; Aggarwal, M. M; Aglieri Rinella, G. M; Agocs, A. G; Agostinelli, A. G; Aguilar Salazar, S. G; Ahammed, Z. G; Ahmad Masoodi, A. G; Ahmad, N. G; Ahn, S. U; Akindinov, A. U; Aleksandrov, D. U;

Strauss, Stefan ; Fischer, Christian S; Kellermann, Christian S

doi: 10.1103/PhysRevLett.109.252001pmid: 23368451

The analytic structure of the nonperturbative gluon propagator contains information on the absence of gluons from the physical spectrum of the theory. We study this structure from numerical solutions in the complex momentum plane of the gluon and ghost Dyson-Schwinger equations in Landau gauge Yang-Mills theory. The resulting ghost and gluon propagators are analytic apart from a distinct cut structure on the real, timelike momentum axis. The propagator violates the Osterwalder-Schrader positivity condition, confirming the absence of gluons from the asymptotic spectrum of the theory.

Stojanović, Vladimir M; Shi, Tao M; Bruder, C. M; Cirac, J. Ignacio

doi: 10.1103/PhysRevLett.109.250501pmid: 23368438

We propose an analog quantum simulation of small-polaron physics using a one-dimensional system of trapped ions acted upon by off-resonant standing waves. This system, envisioned as an array of microtraps, in the single-excitation case allows the realization of the antiadiabatic regime of the Holstein model. We show that the strong excitation-phonon coupling regime, characterized by the formation of small polarons, can be reached using realistic values of the relevant system parameters. Finally, we propose measurements of the quasiparticle residue and the average number of phonons in the ground state, experimental probes validating the polaronic character of the phonon-dressed excitation.