2,034 research outputs found
Visualizing Pure Quantum Turbulence in Superfluid He: Andreev Reflection and its Spectral Properties
Superfluid He-B in the zero-temperature limit offers a unique means of
studying quantum turbulence by the Andreev reflection of quasiparticle
excitations by the vortex flow fields. We validate the experimental
visualization of turbulence in He-B by showing the relation between the
vortex-line density and the Andreev reflectance of the vortex tangle in the
first simulations of the Andreev reflectance by a realistic 3D vortex tangle,
and comparing the results with the first experimental measurements able to
probe quantum turbulence on length scales smaller than the inter-vortex
separation.Comment: 5 pages, 4 figures, and Supplemental Material (2 pages, 2 figures
Cross-sections of Andreev scattering by quantized vortex rings in 3He-B
We studied numerically the Andreev scattering cross-sections of
three-dimensional isolated quantized vortex rings in superfluid 3He-B at
ultra-low temperatures. We calculated the dependence of the cross-section on
the ring's size and on the angle between the beam of incident thermal
quasiparticle excitations and the direction of the ring's motion. We also
introduced, and investigated numerically, the cross-section averaged over all
possible orientations of the vortex ring; such a cross-section may be
particularly relevant for the analysis of experimental data. We also analyzed
the role of screening effects for Andreev reflection of quasiparticles by
systems of vortex rings. Using the results obtained for isolated rings we found
that the screening factor for a system of unlinked rings depends strongly on
the average radius of the vortex ring, and that the screening effects increase
with decreasing the rings' size.Comment: 11 pages, 8 figures ; submitted to Physical Review
Superanalogs of the Calogero operators and Jack polynomials
A depending on a complex parameter superanalog
of Calogero operator is constructed; it is related with the root system of the
Lie superalgebra . For we obtain the usual Calogero
operator; for we obtain, up to a change of indeterminates and parameter
the operator constructed by Veselov, Chalykh and Feigin [2,3]. For the operator is the radial part of the 2nd
order Laplace operator for the symmetric superspaces corresponding to pairs
and , respectively. We will show
that for the generic and the superanalogs of the Jack polynomials
constructed by Kerov, Okunkov and Olshanskii [5] are eigenfunctions of
; for they coinside with the spherical
functions corresponding to the above mentioned symmetric superspaces. We also
study the inner product induced by Berezin's integral on these superspaces
On Spin Calogero-Moser system at infinity
We present a construction of a new integrable model as an infinite limit of Calogero models of N particles with spin. It is implemented in the multicomponent Fock space. Explicit formulas for Dunkl operators, the Yangian generators in the multicomponent Fock space are presented. The classical limit of the system is examined
Self-similarity of rogue wave generation in gyrotrons: Beyond the Peregrine breather
Within the framework of numerical simulations, we study the gyrotron dynamics
under conditions of a significant excess of the operating current over the
starting value, when the generation of electromagnetic pulses with anomalously
large amplitudes ("rogue waves") are realized. We demonstrate that the relation
between peak power and duration of rogue waves is self-similar, but does not
reproduce the one characteristic for Peregrine breathers. Remarkably, the
discovered self-similar relation corresponds to the exponential nonlinearity of
an equivalent Schr\"odinger-like evolution equation. This interpretation can be
used as a theoretical basis for explaining the giant amplitudes of gyrotron
rogue waves
- …