Interacting Spins

D. H. Santamore, E Timmermans

Ultra-cold alkali atoms trapped in two distinct hyperfine states in an external magnetic field can mimic magnetic systems of spin-1/2 particles. We describe the spin-dependent effective interaction as a spin–spin interaction. As a consequence of the zero range, the interaction of spin-1/2 bosons can be described as an Ising or, alternatively, as an XY -coupling. We calculated the spin–spin interaction parameters as a function of the external magnetic field in the degenerate internal state (DIS) approximation. We illustrate the advantage of the spin–spin interaction form by mapping the system of N spin-1/2 bosons confined by a tight trapping potential on that of N spin-1/2 spins coupled via an infinite range interaction.

Sebastian Saner

Da-Chuang Li, Wei-Wei 维韦 Pan 潘, Xing-Dong 兴东 Zhao 赵 +1 more

Abstract Thermal entanglement, as influenced by interaction parameters, is investigated within the general Heisenberg XYZ model. We calculate the relationship between entanglement and the system interaction parameters, including spin–spin interaction parameters (SSIPs) and spin–orbit interaction parameters (SOIPs). By considering various parameter orientations, we identify four optimal combinations of the SSIPs and find that the optimal vector of the spin–orbit interaction aligns with the coordinate axis corresponding to the maximal SSIP component. Furthermore, we obtain three effective optimal combinations of the SOIPs corresponding to the optimal SSIPs, which can maximize the system entanglement when the parameters are tuned accordingly. To demonstrate the feasibility of our results under realistic experimental conditions, we propose an optical lattice scheme with tunable parameters.

Xing Chen, Zhenwei Zhang, Huan Zhao +3 more

We investigate spin squeezing effects of trapped ions in an off-resonance optical potential system using the arbitrary range spin—spin interaction and transverse field model. The collective spin noises at any time are analyzed exactly. The general expression of spin squeezing factor is presented for arbitrary-range spin interaction. For the nearest-neighbor and next-nearest neighbor spin interaction model, the analytic solutions are reduced from the general expressions. It is shown that the maximum spin squeezing is enhanced for the general arbitrary-range spin interaction compared with the nearest-neighbor interaction model as the long-range interaction with arbitrary sites enforces stronger correlation.

Serwan Asaad