Scheme for realizing entanglement concentration via generalized measurements
Ch.-Q. Du, M.Yang, Y. Lu, Zh.-L. Cao+
Key Laboratory of Opto-electronic Information Acquisition and Manipulation, Ministry of Education,
School of Physics & Material Science, Anhui University, 230039 Hefei, People's Republic of China
+School of Electronic Information Engineering, Hefei Normal University, 230061 Hefei, People's Republic of China
Abstract
How to concentrate non-maximally entangled states for
quantum communication is a fundamental problem in quantum
information. In this paper, we will
apply generalized measurements to entanglement concentration of
known non-maximally entangled pure states in arbitrary dimensional
system. How to design the generalized measurements for the
unambiguous discrimination of linearly independent non-orthogonal
states is crucial for the concentration of the known non-maximally
entangled states. The result shows that, any known non-maximally
entangled pure state (for arbitrary dimensional system) can be transformed
to the maximally entangled state only by introducing a qubit as
ancilla and a joint unitary transformation operation on one of the
entangled particles and the ancilla. In addition, because the less entangled state of each
fail round will be re-concentrated too,
the entanglement waste during the concentration process will be greatly reduced.