理想多自由度无相互作用费米气体系统的量子纠缠

Quantum entanglement in ideal noninteracting Fermi gas system with multiple degrees of freedom

对理想的具有自旋1/2和赝旋1/2两自由度费米气体系统的两体纠缠进行研究。结果表明:态空间的扩大,导致系统不超过4个费米子间的两体纠缠表现出类似于自旋1/2自由度的费米气体系统中两费米子间的纠缠分布,而完全不同于其对应的多个费米子间的约化两体纠缠分布;系统两费米子间纠缠存在的相对距离比单个自旋1/2自由度系统时增加了约1.7倍,并且由于两费米子间任一自由度的子纠缠始终为零,因此其中一个自由度的两费米子的子纠缠或量子关联来自于系统的相互作用。

The bipartite entanglement in ideal noninteracting Fermi gas system with spin-l/2 and pseudospin-1/2 degrees of freedom was investigated. Because of the enlarging of state space by two degrees of freedom, the distribution of bipartite entanglement of fermions whose number is no more than four is similar to the entanglement distribution of two fermions and completely different with the distribution of multiparticle entanglement in spin-1/2 noninteraction Fermi gas. The relative entangled distance of two fermions in two degrees of freedom system is about 2. 7 times larger than that of single spin-1/2 system. Entanglement between two fermions of one degree of freedom always equals zero, which means that this entanglement or quantum correlation comes from interactions of system.