Efficient entanglement concentration for partially entangled cluster states with weak cross-Kerr nonlinearity

Abstract

In this paper, we propose an optimal entanglement concentration protocol (ECP) for partially entangled cluster states with the help of the weak cross-Kerr nonlinearity. We can obtain the maximally entangled cluster states assisted with the projection measurements on the additional photons. The protocol is based on optical elements, single polarization photons, cross-Kerr nonlinearity, and the conventional photon detectors, which are feasible with existing experimental technology. Numerical simulation demonstrates that by iterating the entanglement concentration process n = m = 6 times, the ECP has the approximate maximal success probability 100 %. Moreover, the present protocol is also suitable for partially entangled 4N -photon cluster states concentration. All these advantages make this protocol more efficient and more convenient than others in the applications in quantum communication.

Heralded quantum repeater based on the scattering of photons off single emitters using parametric down-conversion source

“…However, the atomic qubits confined in 1D waveguides also inevitably suffer from noises, such as thermal fluctuation and the imperfection of the waveguides. In fact, utilizing entanglement concentration 57 58 59 , one can distill a subset system in a maximally entangled state from less-entangled pure state systems, and using entanglement purification 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 , one can obtain some maximally entangled states from a mixed state ensemble. Now, we start to explain our atomic entanglement purification protocol for bit-flip errors using the scattering of photons off single atoms in 1D waveguides, and its principle is shown in Fig.…”

Linear optics-based entanglement concentration protocols for cluster-type entangled coherent state

“…Our goal is to avoid such degradation in entanglement, and achieve the quantum communication applications with high fidelity. To do so, many ECPs have been proposed and all those existing ECPs have been designed for many different quantum states [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] as well as for Cluster state in different forms [48][49][50][51][52][53][54][55][56]. However, to the best of our knowledge, no ECP has been reported for 4-mode Cluster-type ECS.…”

“…Unfortunately, the Cluster states still interact with the noise just like other multi-partite states and consequently becomes less entangled. To avoid such noise effect, several ECPs have been reported for Cluster states in different forms [48][49][50][51][52][53][54][55][56]. However, we choose to propose two ECPs for 4mode Cluster-type ECS.…”

Hybrid entanglement concentration assisted with single coherent state

“…In 2012, Sheng and Deng first presented the basic principle of efficient single-photon-assisted ECP for partially entangled photon pairs. [35,36] Subsequently, with the help of the single qubit, the ECPs for arbitrary W states, [51][52][53][54][55][56][57][58][59][60][61][62] cluster states, [63][64][65][66][67][68][69] cat states, [71] χ type entangled states, [72] hyper-entangled states, [74][75][76][77] and hybrid entangled states [78] were also proposed.…”