Tunneling vortex dynamics in linearly coupled Bose-Hubbard rings

Abstract

The quantum dynamics of population-balanced fractional vortices and population-imbalanced vortices in an effective two-state bosonic system, made of two coupled discrete circuits with few sites, is addressed within the Bose-Hubbard model. We show that for low on-site interaction, the tunneling of quantized vortices between the rings performs a coherent, oscillating dynamics connecting current states with chiral symmetry. The vortex-flux transfer dually follows the usual sinusoidal particle current of the Josephson effect, in good agreement with a mean-field approximation. Within such regime, the switch of persistent currents in the rings resembles flux-qubit features, and is feasible to experimental realization. On the contrary, strong interatomic interactions suppress the chiral current and lead the system into fragmented condensation. arXiv:1908.01353v1 [cond-mat.quant-gas] 4 Aug 2019 A B q q' J ┴ J q J ┴ J

Josephson oscillations of chirality and identity in two-dimensional solitons in spin-orbit-coupled condensates

“…Among other applications, the Josephson effect in superconductors may be used for design of qubits [27,28]. Josephson oscillations of angular momentum between annular BECs was investigated too [29][30][31][32][33][34][35][36][37][38]. In these contexts, chirality of the wave functions may play an important role [29], [39][40][41][42][43][44].…”

Optical Stern–Gerlach effect via a single traveling-wave light

“…For cold atoms, as we considered here, inter-atom interactions are characterized by repulsive forces [40][41][42]. Atomatom action such as the Casimir-Polder interaction decays exponentially and tends to disappear within an inter-atom distance of R ∼ 1 µm [43].…”

Static properties of two linearly coupled discrete circuits

“…In reference [42] we have studied linear combinations of non-interacting degenerate states, when J ⊥ = 0, that lead to single-particle vortices and fractional vortices. These states correspond to population-imbalanced vortices with current localized in one ring, and to population-balanced fractional vortices, respectively.…”

“…From the point of view of many-body physics, in the presence of a synthetic magnetic field, weakly-and strongly-interacting bosons on two-leg-ladder geometries are well known to disclose intriguing phase diagrams and complex magnetic-like phenomena, where circulating currents can exhibit characteristic Meissner-like and vortex-like patterns [26][27][28][29][30][31][32][33][34], reminiscent of the field dependence of currents in type-II superconductors [35]. In addition, it is worth mentioning that a rich dynamical scenario emerges if one focuses on the possible transfer of persistent currents and vortices between linearly coupled rings [36][37][38][39][40][41][42][43].…”