Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 62: Ultra-cold Atoms, Ions and BEC IV (joint session A/Q)
Q 62.1: Talk
Thursday, March 5, 2026, 14:30–14:45, N 1
Stability of current-carrying Bose-condensed states in a hard-core Bose-Hubbard model with long-range hopping — •Yoshihiro Yabuuchi1,2 and Ippei Danshita2 — 1Osaka Metropolitan University, Japan — 2Kindai University, Japan
The technological progress in the platforms for long-range interacting spin systems have opened new possibilities for exploring emergent quantum many-body phenomena arising from the long-range nature of interactions. Rydberg atom arrays and trapped ions have allowed for realizing systems described by the spin-1/2 XY model with long-range spin-exchange interactions, in which the coupling strength decays algebraically as ∝ r−α, where r is the distance between sites and α the decay exponent. Owing to the theoretical mapping between the spin-1/2 XY model and the hard-core Bose-Hubbard model, the long-range interaction in the former corresponds to the long-range hopping of hard-core bosons where the hopping amplitude decays as ∝ r−α. We theoretically investigate how the long-range hopping affects the stability of current-carrying Bose-condensed states of hard-core bosons [1]. Within a mean-field theory, we find that the critical quasi-momenta for both Landau and dynamical instabilities decrease with decreasing α from a large value and vanishes at α=3, implying that long-range hopping reduces the stability of the current-carrying state. Near α = 3, the critical quasi-momentum for the dynamical instability is proportional to Δ1+Δ with Δ=α−3, meaning that the scaling exponent itself depends on Δ as a remarkable consequence of the long-range nature. [1] Y. Yabuuchi, and I. Danshita, arXiv:2511.14260
Keywords: spin-1/2 XY model; Long-range interactions; Bose-Hubbard model; Bose-Einstein condensation; Linear stability analysis