Quantum entanglement plays crucial roles in quantum information processing. Quantum entangled states have become the key ingredient in the rapidly expanding field of quantum information science. Although the nonclassical nature of entanglement has been recognized for many years, considerable efforts have been taken to understand and characterize its properties recently. In this review, we intro...

The interest on quantum entanglement has dramatically increased during the last 2 decades due to the emerging field of quantum information theory. It turns out that quantum entanglement may be used as basic resources in quantum information processing and communication. The prominent examples are quantum cryptography, quantum teleportation, quantum error correction codes, and quantum computation...

We study the computational complexity of quantum discord (a measure of quantum correlation beyond entanglement), and prove that computing quantum discord is NP-complete. Therefore, quantum discord is computationally intractable: the running time of any algorithm for computing quantum discord is believed to grow exponentially with the dimension of the Hilbert space so that computing quantum disc...

We show how entanglement shared between encoder and decoder can simplify the theory of quantum error correction. The entanglement-assisted quantum codes we describe do not require the dual-containing constraint necessary for standard quantum error-correcting codes, thus allowing us to "quantize" all of classical linear coding theory. In particular, efficient modern classical codes that attain t...

A Poisson model for entanglement optimization in quantum repeater networks is defined in this paper. The nature-inspired multiobjective optimization framework fuses the fundamental concepts of quantum Shannon theory with the theory of evolutionary algorithms. The optimization model aims to maximize the entanglement fidelity and relative entropy of entanglement for all entangled connections of t...

. It was claimed that unconditionally secure quantum bit commitment is impossible due to quantum-computer-assisted-entanglement-attack Recently we have shown that quantum computer-assisted-entanglement-attack can be totally foiled by entanglement and quantum computer. Here we present an alternative un-entanglement based quantum bit commitment scheme. Although the scheme is unconditionally secur...

We give a review on entanglement purification for bipartite and multipartite quantum states, with the main focus on theoretical work carried out by our group in the last couple of years. We discuss entanglement purification in the context of quantum communication, where we emphasize its close relation to quantum error correction. Various bipartite and multipartite entanglement purification prot...

Many previous works on quantum photolithography are based on maximally-entangled states (MES). In this paper, we generalize the MES quantum photolithography to the case where two light beams share a N-photon nonmaximally-entangled state. we investigate the correlations between quantum entanglement and quantum photolithography. It is shown that for nonlocal entanglement between the two light bea...

The quantum entanglements are studied in terms of the invariants under local unitary transformations. A generalized formula of concurrence for N -dimensional quantum systems is presented. This generalized concurrence has potential applications in studying separability and calculating entanglement of formation for high dimensional mixed quantum states. PACS numbers: 03.65.Bz, 89.70.+c SFB 256; B...

Entanglement plays an important role in quantum information processing and communication, such as quantum computation, secret sharing, teleportation, and quantum key distribution [1-3]. Over the last decade, characterizing or/and quantifying entanglement has been recognized as one of central tasks in quantum information science. Correspondingly, there have been many efforts in this direction, f...