Maximally entangled mixed states under nonlocal unitary operations in two qubits

被引：164

作者：

Ishizaka, S ^{[1
]}

Hiroshima, T ^{[1
]}

机构：

[1] NEC Corp Ltd, Fundamental Res Labs, Syst Devices & Fundamental Res, Tsukuba, Ibaraki 3058501, Japan

来源：

PHYSICAL REVIEW A | 2000年 / 62卷 / 02期

关键词：

D O I：

10.1103/PhysRevA.62.022310

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

We propose mixed states in two qubits that have a property that the amount of entanglement of these states cannot be increased by any unitary transformation. The property is proven when the rank of the states is less than 4, and confirmed numerically in the other general cases. The corresponding entanglement of formation specified by its eigenvalues gives an upper bound of that for density matrices with the same eigenvalues. Further, as a simple application of the upper bound of the entanglement of formation, we analyze the entanglement of formation of the state generated by a decohered controlled-NOT gate in the spin-boson model.

引用

页数：4

共 19 条

[1]

Bennett CH, 1996, PHYS REV A, V54, P3824, DOI 10.1103/PhysRevA.54.3824

[2] Separability of very noisy mixed states and implications for NMR Quantum computing [J].