Energetically stable singular vortex cores in an atomic spin-1 Bose-Einstein condensate

We analyze the structure and stability of singular singly quantized vortices in a rotating spin-1 Bose-Einstein condensate. We show that the singular vortex can be energetically stable in both the ferromagnetic and polar phases despite the existence of a lower-energy nonsingular coreless vortex in the ferromagnetic phase. The spin-1 system exhibits energetic hierarchy of length scales resulting from different interaction strengths and we find that the vortex cores deform to a larger size determined by the characteristic length scale of the spin-dependent interaction. We show that in the ferromagnetic phase the resulting stable core structure, despite apparent complexity, can be identified as a single polar core with everywhere nonvanishing axially symmetric density profile. In the polar phase, the energetically favored core deformation leads to a splitting of a singly quantized vortex into a pair of half-quantum vortices that preserves the topology of the vortex outside the extended core region, but breaks the axial symmetry of the core. The resulting half-quantum vortices exhibit nonvanishing ferromagnetic cores.<br/

Особливості демократичного процесу в країнах Балтії

This paper discusses the way the newly formed political entities and the local militias engage in statebuilding practices during Libya's transitional period of 2011-12. Focusing on the encounters between these actors in the security field, it provides insight into the capacity and strategy of national actors to build state structures and to develop the political arrangements that they deem necessary. It does so by identifying the key actors involved, as well as the interactions between them and the constantly evolving relations of control, power and authority. It shows how actors in the security field engage with each other in their efforts to expand and to institutionalize networks and influence, and the competition and alignments with other security actors that are active in the transitional phase and thereafter

Topological interface engineering and defect crossing in ultracold atomic gases

We propose an experimentally feasible scheme for topological interface engineering and show how it can be used for studies of dynamics of topologically nontrivial interfaces and perforation of defects and textures across such interfaces. The method makes use of the internal spin structure of the atoms together with locally applied control of interaction strengths to create many-particle states with highly complex topological properties. In particular, we consider a constructed coherent interface between topologically distinct phases of spinor Bose-Einstein condensates.Comment: 9 pages, 7 figure

Imprinting a topological interface using Zeeman shifts in an atomic spinor Bose–Einstein condensate

We propose to use spatial control of the Zeeman energy shifts in an ultracold atomic gas to engineer an interface between topologically distinct regions. This provides an experimentally accessible means for studying the interface physics of topological defects and textures. Using the spin-1 Bose–Einstein condensate as an example, we find spinor wave functions that represent defects and textures continuously connecting across the interface between polar and ferromagnetic regions induced by spatially varying Zeeman shifts. By numerical energy-minimization we characterize the defect core structures and determine the energetic stability. The techniques proposed could potentially be used in the laboratory to emulate complex interface physics arising, e.g., in cosmological and condensed-matter contexts in both uniform and lattice systems

Helping teammates during product selling: when does it pay off?

Abstract in articl

Helping teammates during product selling: when does it pay off?

Abstract in articl

Everyday Security Practices in Gang-Controlled Neighborhoods in San Salvador

This article looks at the everyday security practices of local residents in violent local orders, where capacities and strategies of state and non-state armed actors to produce regularity and stability are weak and contested. It discusses the case of gang-controlled neighborhoods in the metropolitan area of Greater San Salvador, El Salvador, in the years 2017–2018, when security “provision” of armed state and nonstate actors was weak and contested, and as a result civilians mostly took care of themselves. The article analyzes the main characteristics of local violent orders, the insecurity experiences of local residents, and the everyday practices of local residents to deal with these circumstances. It argues that in neighborhoods where security provision by state and non-state actors is weak and contested, everyday security practices of local residents are key to understanding the functioning and reproduction of the local forms of “disordered order.