Conversion of Knill–Laflamme–Milburn Entanglement to Greenberger–Horne–Zeilinger Entanglement in Decoherence‐Free Subspace

Abstract

In the process of quantum information processing, decoherence effect caused by the coupling between system and its environment will no doubt lead to the error of quantum information stored in the system. To decrease the influence of decoherence effect, decoherence-free subspace (DFS) is introduced. In this work, several schemes to convert the polarized-entangled Knill-Laflamme-Milburn (KLM) states into Greenberger-Horne-Zeilinger (GHZ) states in DFS by using the weak cross-Kerr nonlinearity are proposed. Numerical analysis shows that the proposed schemes have high fidelity and success probability. Due to the unique applications of multi-qubit quantum entangled states in quantum information processing and the robust feature of DFS, the proposed schemes may play positive roles in the future development of quantum communication and quantum information processing tasks.

Nonadiabatic geometric quantum computation of W-state codes using invariant-based reverse engineering

“…Therefore, the dynamic phases can be eliminated by designing gB z (t) = − η sin 2 β/2. In this case, the propagator of the system after a cycling evolution in time interval (14) where Θ ± (T) = ±Θ s , µ(0) = µ 0 , and β(0) = β 0 are assumed.…”

Supplementary document for Direct conversion of Greenberger-Horne-Zeilinger state to Knill-Laflamme-Milburn state in Decoherence-Free Subspace - 5753724.pdf

“…In the previous work, two kinds of schemes namely as the path crossing and non-path crossing schemes were proposed [4]. Here the non-path crossing conversion scheme is investigated for the GHZ to KLM state conversion in this section.…”

Complete conversion of KLM entanglement to GHZ entanglement with error-detected quantum devices

“…The two-qubit KLM state has also been proposed with the help of spontaneous parametric downconversion and implemented in experiments. Because of the different characteristics of the GHZ and KLM states, it becomes a research hotspot focusing on mutual transformation, [31][32][33] where the realization of their conversion will promote the development of QIT.…”