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Université de Fribourg

Moduli space of metrics of nonnegative sectionalor positive ricci curvature on homotopy realprojective spaces

Dessai, Anand ; Gonzalez-Alvaro, David

In: Transactions of the American Mathematical Society, 2019, p. -

We show that the moduli space of metrics of nonnegative sectional curvature on every homotopy $\R P^5$ has infinitely many path components. We also show that in each dimension $4k+1$ there are at least $2^{2k}$ homotopy $\R P^{4k+1}$s of pairwise distinct oriented diffeomorphism type for which the moduli space of metrics of positive Ricci curvature has infinitely many path components....

Université de Fribourg

How network topologies impact project alliance performance: evidence from the movie industry

Zhang, Xin-Jie ; Tang, Yong ; Xiong, Jason ; Wang, Wei-Jia ; Zhang, Yi-Cheng

In: Entropy, 2019, vol. 21, no. 9, p. 859

In many industries, partners are interconnected in project alliances that have limited lifespans and clearly-defined boundaries. The transparency of the movie industry provides a unique opportunity to study how alliance network topologies impact the performance of project alliances from the perspectives of social networks and organization theories. In this work, we compiled a massive movie...

Université de Fribourg

Hund excitations and the efficiency of Mott solar cells

Petocchi, Francesco ; Beck, Sophie ; Ederer, Claude ; Werner, Philipp

In: Physical Review B, 2019, vol. 100, no. 7, p. 075147

We study the dynamics of photoinduced charge carriers in semirealistic models of LaVO3 and YTiO3 polar heterostructures. It is shown that two types of impact ionization processes contribute to the carrier multiplication in these strongly correlated multiorbital systems: The first mechanism involves local spin state transitions, while the second mechanism involves the scattering of...

Université de Fribourg

Entropy-cooled nonequilibrium states of the Hubbard model

Werner, Philipp ; Li, Jianju ; Golež, Denis ; Eckstein, Martin

In: Physical Review B, 2019, vol. 100, no. 15, p. 155130

We show that the recently proposed cooling-by-doping mechanism allows one to efficiently prepare interesting nonequilibrium states of the Hubbard model. Using nonequilibrium dynamical mean field theory and a particle-hole symmetric setup with dipolar excitations to full and empty bands we produce cold photodoped Mott insulating states with a sharp Drude peak in the optical conductivity, a ...

Université de Fribourg

Accounting for effective interactions among charged microgels

Aguirre-Manzo, L. A. ; Ledesma-Motolinía, Mónica ; Rojas-Ochoa, Luis Fernando ; Trappe, Véronique ; Callejas-Fernández, J. ; Haro-Pérez, Catalina ; González-Mozuelos, P.

In: Physical Review E, 2019, vol. 100, no. 3, p. 032602

We introduce a theoretical approach to describe structural correlations among charged permeable spheres at finite particle concentrations. This theory explicitly accounts for correlations among microions and between microions and macroions and allows for the proposal of an effective interaction among macroions that successfully captures structural correlations observed in poly- N -isopropyl...

Université de Fribourg

Light induced inverse-square law interactions between nanoparticles: “mock gravity” at the nanoscale

Luis-Hita, J. ; Marqués, M. I. ; Delgado-Buscalioni, R. ; Sousa, N. de ; Froufe-Pérez, L. S. ; Scheffold, Frank ; Sáenz, J. J.

In: Physical Review Letters, 2019, vol. 123, no. 14, p. 143201

The interaction forces between identical resonant molecules or nanoparticles, optically induced by a quasimonochromatic isotropic random light field, are theoretically analyzed. In general, the interaction force exhibits a far-field oscillatory behavior at separation distances larger than the light wavelength. However, we show that the oscillations disappear when the frequency of the random...

Université de Fribourg

From chaos to many-body localization: some introductory notes

Chotorlishvili, L. ; Stagraczyński, S. ; Schüler, Michael ; Berakdar, J.

In: Acta Physica Polonica A, 2019, vol. 135, no. 6, p. 1155–1162

Staring from the kicked rotator as a paradigm for a system exhibiting classical chaos, we discuss the role of quantum coherence resulting in dynamical localization in the kicked quantum rotator. In this context, the disorder-induced Anderson localization is also discussed. Localization in interacting, quantum many-body systems (many-body localization) may also occur in the absence of...

Université de Fribourg

Colloidal dynamics and elasticity of dense wax particle suspensions over a wide range of volume fractions when tuning the softness by temperature

Yoon, Jiwon ; Scheffold, Frank ; Ahn, Kyung Hyun

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019, vol. 576, p. 1–8

We report on the colloidal dynamics and rheology of liquid droplet emulsions and solid particle suspensions over a wide range of volume fractions. Diffusing wave spectroscopy and rheometry were utilized to study the micro/macroscale properties of 1-eicosene wax particles dispersed in water. By changing the temperature, the wax droplets change their properties from soft to hard or vice versa,...

Université de Fribourg

Novel reference-free methods for the determination of the instrumental response of Laue-type bent crystal spectrometers

Szlachetko, Monika ; Hoszowska, Joanna ; Szlachetko, Jakub ; Dousse, Jean-Claude

In: Journal of Analytical Atomic Spectrometry, 2019, vol. 34, no. 11, p. 2325–2332

We report on novel reference-free methods to determine the instrumental resolution of transmission-type bent crystal spectrometers. The novel methods are based on the measurements of a selected X-ray line in several orders of diffraction. It is shown that the angular broadening of the spectrometer and the natural linewidth of the selected transition can be obtained directly from the novel...

Université de Fribourg

Magnetic-field effects on one-dimensional Anderson localization of light

Schertel, Lukas ; Irtenkauf, Oliver ; Aegerter, Christof M. ; Maret, Georg ; Aubry, Geoffroy J.

In: Physical Review A, 2019, vol. 100, no. 4, p. 043818

Transport of coherent waves in multiple-scattering media may exhibit fundamental, nonintuitive phenomena such as halt of diffusion by disorder called Anderson localization. For electromagnetic waves, this phenomenon was observed only in one and two dimensions so far. However, none of these experiments studied the contribution of reciprocal paths nor their manipulation by external fields. In...