arXiv subjects

N. Ghazanfari

Publications and source records attributed to N. Ghazanfari.

3 recordsLinked to original sources

arXiv2017

Spectral splits of neutrinos as a BCS-BEC crossover type phenomenon

We show that the spectral split of a neutrino ensemble which initially consists of electron type neutrinos, is analogous to the BCS-BEC crossover already observed in ultra cold atomic gas experiments. Such a neutrino ensemble mimics the deleptonization burst of a core collapse supernova. Although these two phenomena belong to very different domains of physics, the propagation of neutrinos from highly interacting inner regions of the supernova to the vacuum is reminiscent of the evolution of Cooper pairs between weak and strong interaction regimes during the crossover. The Hamiltonians and the corresponding many-body states undergo very similar transformations if one replaces the pair quasispin of the latter with the neutrino isospin of the former.

astro-ph.HE↗

arXiv2014

Vortex lattices in dipolar two-component Bose-Einstein condensates

We consider a rapidly rotating two-component Bose-Einstein condensate with short-range s-wave interactions as well as dipolar coupling. We calculate the phase diagram of vortex lattice structures as a function of the intercomponent s-wave interaction and the strength of the dipolar interaction. We find that the long-range interactions cause new vortex lattice structures to be stable and lead to a richer phase diagram. Our results reduce to the previously found lattice structures for short-range interactions and single-component dipolar gases in the corresponding limits.

cond-mat.quant-gas↗

arXiv2009

Rapidly Rotating Fermions in an Anisotropic Trap

We consider a cold gas of non-interacting fermions in a two dimensional harmonic trap with two different trapping frequencies $ω_x \leq ω_y$, and discuss the effect of rotation on the density profile. Depending on the rotation frequency $Ω$ and the trap anisotropy $ω_y/ω_x$, the density profile assumes two qualitatively different shapes. For small anisotropy ($ω_y/ω_x \ll \sqrt{1+4 Ω^2/ω_x^2}$), the density consists of elliptical plateaus of constant density, corresponding to Landau levels and is well described by a two dimensional local density approximation. For large anisotropy ($ω_y/ω_x \gg \sqrt{1+4 Ω^2/ω_x^2}$), the density profile is Gaussian in the strong confining direction and semicircular with prominent Friedel oscillations in the weak direction. In this regime, a one dimensional local density approximation is well suited to describe the system. The crossover between the two regimes is smooth where the step structure between the Landau level edges turn into Friedel oscillations. Increasing the temperature causes the step structure or the Friedel oscillations to wash out leaving a Boltzmann gas density profile.

cond-mat.quant-gas↗