Physical Review Letters

Bellm, S; Lower, J; Weigold, E; Mueller, D. W

doi: 10.1103/PhysRevLett.104.023202pmid: 20366592

We present fully differential state-resolved experimental data for the dissociative ionization of molecular hydrogen induced through electron impact. Molecular-frame ionization cross sections are derived for transitions from the X 1 Σ g + molecular ground state to the 1 s σ g , 2 p σ u , 2 s σ g , and 2 p π u states of H 2 + . For transitions to the 2 s σ g and 2 p π u states, a strong orientation dependence in the cross sections is revealed, with “side-on” preferred to “end-on” collisions and a propensity for the fragment proton to emerge along the normal to the scattering plane.

Rozenfeld, Hernán D; Song, Chaoming D; Makse, Hernán A

doi: 10.1103/PhysRevLett.104.025701pmid: 20366610

We show that renormalization group (RG) theory applied to complex networks is useful to classify network topologies into universality classes in the space of configurations. The RG flow readily identifies a small-world–fractal transition by finding (i) a trivial stable fixed point of a complete graph, (ii) a nontrivial point of a pure fractal topology that is stable or unstable according to the amount of long-range links in the network, and (iii) another stable point of a fractal with shortcuts that exist exactly at the small-world–fractal transition. As a collateral, the RG technique explains the coexistence of the seemingly contradicting fractal and small-world phases and allows us to extract information on the distribution of shortcuts in real-world networks, a problem of importance for information flow in the system.

Longo, Paolo

doi: 10.1103/PhysRevLett.104.023602pmid: 20366595

We present a detailed analysis of the dynamics of photon transport in waveguiding systems in the presence of a two-level system. In these systems, quantum interference effects generate a strong effective optical nonlinearity on the few-photon level. We clarify the relevant physical mechanisms through an appropriate quantum many-body approach. Based on this, we demonstrate that a single-particle photon-atom bound state with an energy outside the band can be excited via multiparticle scattering processes. We further show that these trapping effects are robust and, therefore, will be useful for the control of photon entanglement in solid-state based quantum-optical systems.

Bark, R. A; Sharpey-Schafer, J. F; Maliage, S. M; Madiba, T. E; Komati, F. S; Lawrie, E. A; Lawrie, J. J; Lindsay, R. J; Maine, P. J; Mullins, S. M; Murray, S. H; Ncapayi, N. J; Ramashidza, T. M; Smit, <?format ?>F. D; Vymers, P. D

McGuffey, C; Thomas, A. G; Schumaker, W. G; Matsuoka, T. G; Chvykov, V. G; Dollar, F. J; Kalintchenko, G. J; Yanovsky, V. J; Maksimchuk, A. J; Krushelnick, K. J

doi: 10.1103/PhysRevLett.104.025004pmid: 20366605

Otto, Florian ; Bilušić, Ante ; Babić, Dinko ; Vodolazov, Denis Yu; Sürgers, Christoph Yu; Strunk, Christoph Yu

doi: 10.1103/PhysRevLett.104.027005pmid: 20366621

We investigate nonlocal vortex motion in weakly pinning a -NbGe nanostructures, which is driven by a transport current I and remotely detected as a nonlocal voltage V nl . At a high I of a given polarity, V nl changes sign dramatically. This is followed by V nl becoming even in I , with the opposite sign at low and high temperatures T . These findings can be explained by a Nernst-like effect resulting from local electron overheating (low T ), and a magnetization enhancement due to a nonequilibrium quasiparticle distribution that leads to a gap enhancement near the vortex core (high T ).

Lancia, L; Marquès, J.-R; Nakatsutsumi, M; Riconda, C; Weber, S; Hüller, S; Mančić, A; Antici, P; Tikhonchuk, V. T; Héron, A. T; Audebert, P. T; Fuchs, J. T

doi: 10.1103/PhysRevLett.104.025001

Biswas, Tirthabir ; Cembranos, Jose A; Kapusta, Joseph I

doi: 10.1103/PhysRevLett.104.021601pmid: 20366584

We develop the finite temperature theory of p -adic string models. We find that the thermal properties of these nonlocal field theories can be interpreted either as contributions of standard thermal modes with energies proportional to the temperature, or inverse thermal modes with energies proportional to the inverse of the temperature, leading to a thermal duality at leading order (genus one) analogous to the well-known T duality of string theory. The p -adic strings also recover the asymptotic limits (high and low temperature) for arbitrary genus that purely stringy calculations have yielded. We also discuss our findings surrounding the nature of the Hagedorn transition.

Sokolov, V; Wei, X; Sen, A. K

doi: 10.1103/PhysRevLett.104.025002pmid: 20366603

The unique complementary roles of ion acoustic damping and zonal-flow (ZF) shearing in the saturation of ion temperature gradient modes (ITG) has been experimentally demonstrated using stabilizing and destabilizing feedback techniques. This was done in the context of experimental studies of ZF scalings over a wide parameter range. Furthermore, the scaling of ZF amplitude with that of ITG via increasing ITG drive through increasing ion temperature gradient via rf heating reveals an expected monotonic behavior.

Arévalo, Edward

doi: 10.1103/PhysRevLett.104.023902pmid: 20366597

X waves are spatiotemporal optical waves with intriguing superluminal and subluminal characteristics. Here we theoretically show that for a given initial carrier frequency of the system localized waves with genuine superluminal or subluminal group velocity can emerge from initial X waves in nonlinear optical systems with normal group velocity dispersion. Moreover, we show that this temporal behavior depends on the wave detuning from the carrier frequency of the system and not on the particular X -wave biconical form. A spatial counterpart of this behavior is also found when initial X waves are boosted in the plane transverse to the direction of propagation, so a fully spatiotemporal motion of localized waves can be observed.