실적년도 | 2012년 |
---|---|
논문구분 | 국외 |
총저자 | Kil-Chan Ha, Seung-Hyeok Kye |
학술지명 | Journal of Mathematical Physics |
권(Vol.) | 53 |
호(No.) | 10 |
게재년월 | 2012년 10월 |
Impact Factor | |
SCI 등재 | SCI |
비고 |
We introduce the notions of positive and copositive types for entanglement witnesses, depending on the distance to the positive part and copositive part. An entanglement witness W is of positive type if and only if its partial transpose is of copositive type. We show that if the structural physical approximation (SPA) of W is separable, then W should be of copositive type, and the SPA of is never separable unless W is of both positive and copositive types. This shows that the SPA conjecture is meaningful only for those of copositive type. We provide examples to show that the SPA conjecture fails even for the case of copositive types.