Related papers: Dynamical Casimir effect for magnons in a spinor B…
The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S = 1/2 moments on a quasi-2D square lattice. We have investigated its spin dynamics by inelastic neutron scattering experiments on single crystals with an energy…
In the first part we discuss how the BEC picture for magnons is modified by anisotropies induced by spin-orbit coupling. In particular we focus on the effects of antisymmetric spin interactions and/or a staggered component of the $g$…
We theoretically propose and numerically realize spin echo in a spinor Bose--Einstein condensate (BEC). We investigate the influence on the spin echo of phase separation of the condensate. The equation of motion of the spin density exhibits…
Bose-Einstain condensation occurs at an appropriate density of bosonic particles, depending on their mass and temperature. We were able to experimentally observe the transition from the spin wave regime to the magnon Bose-Einstein condensed…
We analyze the physics of spin-3 Bose-Einstein condensates, and in particular the new physics expected in on-going experiments with condensates of Chromium atoms. We first discuss the ground-state properties, which, depending on still…
The Bose-Einstein condensation of bound pairs made of equally and oppositely charged fermions in a magnetic field is investigated using a relativistic model. The Gaussian fluctuations have been taken into account in order to study the…
We theoretically investigate four types of dynamical instability, in particular the periodic and oscillatory type $I_O$, in an anti-ferromagnetic spin-1 Bose-Einstein condensate in a nonzero magnetic field, by employing the coupled-mode…
We study the time-evolution of an optically trapped spinor Bose-Einstein condensate under the influence of a dominating magnetic bias field in the z-direction, and a perpendicular smaller field that couples the spinor states. We show that…
We investigate the St\"{u}ckelberg oscillations of a spin-1 Bose-Einstein condensate subject to a spatially inhomogeneous transverse magnetic field and a periodic longitudinal field. We show that the time-domain St\"{u}ckelberg oscillations…
We analyze the structure of spin-1 Bose-Einstein condensates in the presence of a homogenous magnetic field. We classify the homogenous stationary states and study their existence, bifurcations, and energy spectra. We reveal that the phase…
$^{23}$Na spin-1 Bose-Einstein condensates are used to experimentally demonstrate that mean-field physics beyond the single-mode approximation can be relevant during the non-equilibrium dynamics. The experimentally observed spin oscillation…
We study the response of a quantum magnet with spin-orbit coupling (SOC) to a Zeeman field by constructing effective actions and performing Renormalization Group (RG) analysis. There are several novel classes of quantum phase transitions at…
We study the macroscopic quantum tunneling of magnetization of the F=1 spinor condensate interacting through dipole-dipole interaction with an external magnetic field applied along the longitudinal or transverse direction. We show that the…
If the boundary conditions of the quantum vacuum are changed in time, quantum field theory predicts that real, observable particles can be created in the initially empty modes. Here, we realize this effect by changing the boundary…
We observe multi-step condensation of sodium atoms with spin $F=1$, where the different Zeeman components $m_F=0,\pm 1$ condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the…
We observe coherent spin oscillations in an antiferromagnetic spin-1 Bose-Einstein condensate of sodium. The variation of the spin oscillations with magnetic field shows a clear signature of nonlinearity, in agreement with theory, which…
We study the thermodynamic properties of a neutral vector boson gas in presence of a constant magnetic field, by means of a semi-classical approach that allows to introduce the spin in the non-relativistic spectrum of the bosons.…
We present a study of magnetic field induced quantum phase transitions in insulating systems. A generalized scaling theory is used to obtain the temperature dependence of several physical quantities along the quantum critical trajectory…
The effects of modulating spin-orbit coupled Bose-Einstein condensates are analytically studied. A sinusoidal driving of the coupling amplitude is shown to induce significant changes in the energy bands and in the associated spin-momentum…
Polarization-dependent phase-contrast imaging is used to spatially resolve the magnetization of an optically trapped ultracold gas. This probe is applied to Larmor precession of degenerate and nondegenerate spin-1 $^{87}$Rb gases.…