22,661 research outputs found
Quantum entangled ground states of two spinor Bose-Einstein condensates
We revisit in detail the non-mean-field ground-state phase diagram for a
binary mixture of spin-1 Bose-Einstein condensates including quantum
fluctuations. The non-commuting terms in the spin-dependent Hamiltonian under
single spatial mode approximation make it difficult to obtain exact
eigenstates. Utilizing the spin z-component conservation and the total spin
angular momentum conservation, we numerically derive the information of the
building blocks and evaluate von Neumann entropy to quantify the ground states.
The mean-field phase boundaries are found to remain largely intact, yet the
ground states show fragmented and entangled behaviors within large parameter
spaces of interspecies spin-exchange and singlet-pairing interactions.Comment: 7 pages, 5 figure
Rigorous Proof of Pseudospin Ferromagnetism in Two-Component Bosonic Systems with Component-Independent Interactions
For a two-component bosonic system, the components can be mapped onto a
pseudo-spin degree of freedom with spin quantum number S=1/2. We provide a
rigorous proof that for a wide-range of real Hamiltonians with component
independent mass and interaction, the ground state is a ferromagnetic state
with pseudospin fully polarized. The spin-wave excitations are studied and
found to have quadratic dispersion relations at long wave length.Comment: 4 pages, no figur
A mechanism to pin skyrmions in chiral magnets
We propose a mechanism to pin skyrmions in chiral magnets by introducing
local maximum of magnetic exchange strength, which can be realized in chiral
magnetic thin films by engineering the local density of itinerate electrons.
Thus we find a way to artificially control the position of a single skyrmion in
chiral magnetic thin films. The stationary properties and the dynamical pinning
and depinning processes of an isolated skyrmion around a pinning center are
studied. We do a series of simulations to show that the critical current to
depin a skyrmion has linearly dependence on the pinning strength. We also
estimate the critical current to have order of magnitude
10^{7}\sim10^{8}A/m^{2}
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