Local transformation of mixed states of two qubits to Bell diagonal states
Abstract
The optimal entanglement manipulation for a single copy of mixed states of two qubits is to transform it to a Bell diagonal state. In this paper we derive an explicit form of the local operation that can realize such a transformation. The result obtained is universal for arbitrary entangled two-qubit states and it discloses that the corresponding local filter is not unique for density matrices with rank n=2 and can be exclusively determined for that with n=3 and 4. As illustrations, a four-parameter family of mixed states are explored, the local filter as well as the transformation probability are given explicitly, which verify the validity of the general result.
- Publication:
-
Physical Review A
- Pub Date:
- May 2002
- DOI:
- 10.1103/PhysRevA.65.052318
- arXiv:
- arXiv:quant-ph/0203092
- Bibcode:
- 2002PhRvA..65e2318C
- Keywords:
-
- 03.67.Hk;
- 03.65.Ud;
- Quantum communication;
- Entanglement and quantum nonlocality;
- Quantum Physics
- E-Print:
- 5 pages, to be published in Phys. Rev. A