398 research outputs found
Universal Borromean Binding in Spin-Orbit Coupled Ultracold Fermi Gases
Borromean rings and Borromean binding, a class of intriguing phenomena as
three objects are linked (bound) together while any two of them are unlinked
(unbound), widely exist in nature and have been found in systems of biology,
chemistry and physics. Previous studies have suggested that the occurrence of
such a binding in physical systems typically relies on the microscopic details
of pairwise interaction potentials at short-range, and is therefore
non-universal. Here, we report a new type of Borromean binding in ultracold
Fermi gases with Rashba spin-orbit coupling, which is {\it universal} against
short-range interaction details, with its binding energy only dependent on the
s-wave scattering length and the spin-orbit coupling strength. We show that the
occurrence of this universal Borromean binding is facilitated by the symmetry
of the single-particle dispersion under spin-orbit coupling, and is therefore
{\it symmetry-selective} rather than interaction-selective. The state is robust
over a wide range of mass ratio between composing fermions, which are
accessible by Li-Li, K-K and K-Li mixtures in cold atoms experiments. Our
results reveal the importance of symmetry factor in few-body physics, and shed
light on the emergence of new quantum phases in a many-body system with exotic
few-body correlations.Comment: 6+1.5 pages, 5 figures, published versio
Non-Hermitian skin effect in a spin-orbit-coupled Bose-Einstein condensate
We study a Bose-Einstein condensate of ultracold atoms subject to a
non-Hermitian spin-orbit coupling, where the system acquires non-Hermitian skin
effect under the interplay of spin-orbit coupling and laser-induced atom loss.
The presence of the non-Hermitian skin effect is confirmed through its key
signatures in term of the spectral winding under the periodic boundary
condition, the accumulation of eigen wavefunctions at boundaries under an open
boundary condition, as well as bulk dynamics signaled by a directional flow. We
show that the bulk dynamics in particular serves as a convenient signal for
experimental detection. The impact of interaction and trapping potentials are
also discussed based on non-Hermitian Gross-Pitaevskii equations. Our work
demonstrates that the non-Hermitian skin effect and its rich implications in
topology, dynamics and beyond are well within reach of current cold-atom
experiments.Comment: 6 pages, 4 figure
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