ua nt - p h / 06 09 05 0 v 3 1 8 Se p 20 06 NPT Bound Entanglement - The Problem Revisited

ua nt - p h / 06 09 05 0 v 2 1 1 Se p 20 06 Bound Entangled States With Negative Partial Transpose Exist !

We prove the existence of bound entangled states with negative partial transpose (NPT) in any d×d(d ≥ 3) Hilbert space with simple assumptions on Schmidt rank two states. We have assumed that the Schmidt rank two states should satisfy some bounds. Obviously the class of NPT bound entangled states belong to the class of conjectured to be bound entangled states by Divincenzo et.al [Phys. Rev. A, ...

ua nt - p h / 05 09 21 8 v 1 3 0 Se p 20 05 N - qubit entanglement via the J 2 y - type collective interaction

ar X iv : q ua nt - p h / 05 06 09 5 v 1 1 3 Ju n 20 05 Schmidt states and positivity of linear maps

Using pure entangled Schmidt states, we show that m-positivity of a map is bounded by the ranks of its negative Kraus matrices. We also give an algebraic condition for a map to be m-positive. We interpret these results in the context of positive maps as entanglement witnesses, and find that only 1-positive maps are needed for testing entanglement.

ua nt - p h / 00 09 06 3 v 1 1 4 Se p 20 00 Entanglement of Formation of an Arbitrary State of Two Rebits ∗

We consider entanglement for quantum states defined in vector spaces over the real numbers. Such real entanglement is different from entanglement in standard quantum mechanics over the complex numbers. The differences provide insight into the nature of entanglement in standard quantum theory. Wootters [Phys. Rev. Lett. 80, 2245 (1998)] has given an explicit formula for the entanglement of forma...

ua nt - p h / 06 05 18 5 v 3 3 1 Ja n 20 09 Single qubit , two qubit gates and no signalling principle

In this work we investigate that whether one can construct single and two qubit gates for arbitrary quantum states from the principle of no signalling. We considered the problem for Pauli gates, Hadamard gate, C-Not gate.