三量子位和四量子位Heisenberg XY链中的纠缠与自旋压缩(英文)

研究了三量子位和四量子位Heisenberg XY链中的基态纠缠与自旋压缩,给出了纠缠C和自旋压缩参数ξ2的解析表达式.结果表明,当外部磁场B大于某一临界值Bc时,纠缠与自旋压缩等价,即纠缠意味着自旋压缩,反之亦然.对三量子位情形,Bc=J(4-3γ2)1/2-1];对四量子位情形,Bc可以通过数值方法进行求解.

Entanglement and spin squeezing in the three-and four-qubit Heisenberg XY spin chain

We investigate the pairwise entanglement and spin squeezing in the ground state of the three- and four-qubit Heisenberg XY spin chain and give analytical expressions of the concurrence C and the spin squeezing parameter ξ2. Our results show that the entanglement is equivalent to spin squeezing (i.e. the entanglement implies spin squeezing and vice versa) if the external magnetic field B is above a certain critical value Bc, where for the three-qubit case, Bc=J(4-3γ2)1/2-1], and for the four-qubit case, Bc can be obtained numerically.