Phantom excitations generate spin helix structures in spin chains: from integrable systems to cold atoms.
We demonstrate the existence of a special chiral ?phantom? mode analogical to a Goldstone mode in the anisotropic quantum XXZ Heisenberg spin chain. The phantom excitations contribute zero energy, and a fixed quantum of momentum. The mode originates from special string-type solutions of the Bethe ansatz equations with unbounded rapidities, the phantom Bethe roots. The simplest representative of ?phantom? Bethe states is a factorized state with helicoidal magnetization profile, the spin-helix state. Spin helix eigenstates were focused on in recent cold atom experiments, and led to further surprising findings.
- 2022-10-07 12:00 - 13:00
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