Spectra of low-lying elementary excitations are critical to characterize properties of bosonic quantum fluids. Usually these spectra are difficult to observe, due to low occupation of non-condensate states compared to the ground state. Recently, low-threshold Bose-Einstein condensation was realised in a symmetry-protected bound state in the continuum, at a saddle point, thanks to coupling of this electromagnetic resonance to semiconductor excitons.
View Article and Find Full Text PDFQuantum vortices are the quantized version of classical vortices. Their center is a phase singularity or vortex core around which the flow of particles as a whole circulates and is typical in superfluids, condensates and optical fields. However, the exploration of the motion of the phase singularities in coherently-coupled systems is still underway.
View Article and Find Full Text PDFQuantum vortices are the analogue of classical vortices in optics, Bose-Einstein condensates, superfluids and superconductors, where they provide the elementary mode of rotation and orbital angular momentum. While they mediate important pair interactions and phase transitions in nonlinear fluids, their linear dynamics is useful for the shaping of complex light, as well as for topological entities in multi-component systems, such as full Bloch beams. Here, setting a quantum vortex into directional motion in an open-dissipative fluid of microcavity polaritons, we observe the self-splitting of the packet, leading to the trembling movement of its center of mass, whereas the vortex core undergoes ultrafast spiraling along diverging and converging circles, in a sub-picosecond precessing fashion.
View Article and Find Full Text PDFThe complete mitochondrial genomes of aphids Aphis fabae mordvilkoi, A. craccivora, Myzus persicae from Aphidinae as well as Therioaphis tenera and Appendiseta robiniae from Calaphidinae were sequenced and compared with the genomes of other aphid species. A.
View Article and Find Full Text PDFIn this paper we calculate the energies of ground and excited states of two opposite charge carriers confined on a single- or double-wall cylindrical surface. A nontrivial dependence of excited state energies on cylinder radius value (for the case of a single-wall cylinder) is found, and the explanation of this behavior is based on symmetry properties of the corresponding wavefunctions. The crossover from a one-dimensional problem to a two-dimensional one with increase of the radius value is discussed in detail.
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