The Entanglement Of The REW States

Quantum entanglement as a physical resource plays a very important role in quantum information and quantum computation. Therefore, the characterization, detection, clas-sification and quantitative research of quantum entanglement are very meaningful work in theoretical research and practical applications. Multipartite quantum entanglement is very complex so that there are many issues that need further research, particular-1y the quantitative research of multipartite entanglement. In this paper, we study the REW states which is an important class of multipartite quantum states and calculate their k-ME concurrence. Then we portray the REW states’entanglement and study the k-nonseparability of them.The first chapter, some basic knowledge used in this paper is given.In the second chapter, we calculate the k-ME concurrence of the n-qubit real equally weighted states (REW states). Let M be the number of minuses in the REW states.When M = 1, the REW states |ψf1 〉 are genuine entangled states, their k-ME con-currence is where A represents all the k-partition of the n qubits, specificallyWhen M = 2, we calculate the k-ME concurrence of the REW states as follows.If k= 2,n - 1,n, and there is only one different qubit between the n-qubit two computational basis states with coefficients -1, we get C2-ME(|ψf2 〉= 0, and the states |ψf2 〉 are 2-separable in this case.If there are at least two different qubits between the n-qubit two computational basis states with coefficients一1.thenAnd we get Ck ME(|ψf1 〉)= min{gA(1)(k),GA(2)(k)},(k≠2,n-1,n), where A(1)∩ A(2)=0,A(1)∪ A(2)=A,and A represents all the k-partition of the n qubits.When M =s(3 ≤ s ≤2n-1,s ∈Z+),we get n-ME concurrence of the REW statesif s=2n-1,Cn-ME(|ψfs 〉) = 0,the states |ψfs 〉are n-separable；if 3 ≤ s < 2n-1, Cn-ME(|ψfs 〉)>0,the states |ψfs 〉are n-nonseparable,which means that there exists entanglement in this class of states.