Deterministic Entangled Pairs

Zheng Zhou, Guang Can Guo

Fumiaki Morikoshi, Masato Koashi

Deterministic extraction of Bell pairs from a finite number of partially entangled pairs is discussed. We derive the maximum number of Bell pairs that can be obtained with probability 1 by local operations and classical communication. It is proved that the optimal deterministic concentration needs only a two-pair collective manipulation in each step, and that a collective manipulation of all entangled pairs is not necessary. Finally, this scheme reveals an entanglement measure for the deterministic concentration.

Wen-Zhao Zhang, Wendong Li, Shi Peng +1 more

According to the Nielsens theorem and the basic idea of entanglement concentration, we improve and extend the deterministic entanglement concentration protocol that extracts one pair of maximally entangled particles out of two pairs of non-maximally entangled particles, thus establishing a deterministic entanglement concentration protocol that extracts two pairs of maximally entangled particles out of three pairs of non-maximally entangled particles in the way of the classical communication and local operation and the specific positive operator-valued measure. This is helpful for establishing a deterministic entanglement concentration protocol that extracts k pairs of maximally entangled particles out of n pairs of non-maximally entangled particles.

Goswami, Abhirup

Quantum repeaters are the most promising approach for distributing entanglement over long distances. Recent approaches to develop quantum repeaters involve the use of deterministic entangled photon pair sources. On the other hand heralded entangled photon pair sources have been proposed independently both with parametric down conversion source and single photon sources. We modify the latter scheme to implement it as an on demand entangled photon pair source and analyse its performance considering inefficient detectors, inefficient quantum memories and inefficient single photon sources. We conclude that with the current state of art, generation of high fidelity deterministic entangled photon pairs is possible with moderate efficiency. We then compare the results to the deterministic entangled photon pair source obtainable using parametric down conversion source and conclude that the single photon scheme described in this thesis is more practical for such an implementation.

Ingemar Bengtsson, Karol Życzkowski