Study of Quantum Entanglement Purification of Mixed States
Yi-hsiu Liu1*, Hsi-sheng Goan1
1Department of Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Yi-hsiu Liu,
Transmitting a quantum state with high fidelity to a distant place is still a challenge even though there are some ramarkable breakthroughs recently. To achieve this goal, quantum teleportation, which distributes an unknown state to the other place, becomes an option. But the fidelity of a teleported state depends on the fidelity of distributing the prepared entangled pairs, through which Alice and Bob can implement quantum teleportation. Besides, quantum entanglement plays an vital role in quantum information and quantum communication, such as in quantum key distribution (QKD), quantum teleportation (QT), and Quantum Superdense coding. Because a quantum state is more fragile than a classical signal, when transmitting a quantum state through a quantum channel a quantum state tends to be disturbed by noise from environment so that a pure state becomes a mixed state. We introduce some protocols through which one can enhance the fidelity of mixed entangled pairs when simultaneous bit-flip error and phase-flip error occur. Furthermore, we propose a deterministic protocol purifying mixed states of Bell basis diagonal states to a desired pure entangled state by passive linear optical components and single-photon detectors. Besides, unique from other deterministic protocols, our proposed protocol has deterministic outputs, does not require postselection, and allow users to know when the desired outputs come out.

Keywords: Entanglement Purification Protocol, Quantum Entanglement Purification, Quantum Teleportation, Polarization Beam Splitter