Search

In this paper, we investigate the convergence behavior of the fixed-point search algorithm with two arbitrary equal phase shifts for any number of iterations. We show that no matter what the initial deviation is, the algorithm converges to the target state with certainty for phase shifts between 0 and π∕2, and to the target state with the success probabilities of at least 80% and at least 66% for phase shifts between π∕2 and arccos(-1/4) and between arccos(-1/4) and 2π/3, respectively, while the algorithm does not converge for phase shifts between 2π/3 and π. [ABSTRACT FROM AUTHOR]

Abstract: Grover recently presented the fixed-point search algorithm. In this Letter, we study the fixed-point search algorithm obtained by replacing equal phase shifts of by different phase shifts. [Copyright &y& Elsevier]

Abstract: We put forward an alternative approach to the SLOCC classification of three-qubit and four-qubit systems. By directly solving matrix equations, we obtain the relations satisfied by the amplitudes of states. The relations are readily tested since in them only addition, subtraction and multiplication occur. [Copyright &y& Elsevier]

We show the impossibility of reversing or complementing any quantum state and give the generalization of the no-cloning theorem to other forbidden evolutions and impossible processes. [ABSTRACT FROM AUTHOR]