Introducing classical fields, we can transfer entanglement completely from discrete qubits into entangled coherent state. The entanglement also can be retrieved from the continuous-variable state of the cavities to the atomic qubits. Via postselection measure, atomic entangled state and entangled coherent state can be mutual transformed fully.
Complementarity and entanglement are fundamental features of Quantum Mechanics that were recently related in triality equalities that involve quantum coherence, the wave aspect of a qubit, and quantum predictability and quantum entanglement, the particle aspect of a qubit. In this article, we give an operational connection between redictability and entanglement in entanglement swapping from initially partially entangled states. For this, we show that the predictability of the pre-measurement one-qubit density matrix is directly related to the probability of the partially entangled component of…
We propose a scheme for distillation of free bipartite entanglement from bipartite bound-entangled states. The crucial element of our scheme is an ancillary system that is coupled to the initial bound-entangled state via appropriate weak measurements. We show that in this protocol free entanglement can be always generated with nonzero probability by using a single copy of the bound-entangled state. We also derive a lower bound on the entanglement cost of the protocol, and conclude that, on average, applying weaker measurements results in relatively higher values of free entanglement as well as…
Genuine entanglement is the strongest form of multipartite entanglement. Genuinely entangled pure states contain entanglement in every bipartition and as such can be regarded as a valuable resource in the protocols of quantum information processing. A recent direction of research is the construction of genuinely entangled subspaces -- the class of subspaces consisting entirely of genuinely multipartite entangled pure states. In this paper we present several methods of construction of such subspaces including those of maximal possible dimension. The approach is based on the correspondence betwe…
Evaluation of two different entanglement measures on a bound entangled state
我们考虑了混合三量子比特束缚纠缠态，它被定义为与不可拓积基互补的子空间上的归一化投影子[C. H. Bennett et.例如，物理修订信函82，5385（1999）]。利用没有乘积态存在于该态的支撑中的事实，我们通过提供由“最小纠缠”态构成的子空间的基来计算它的纠缠。该方法是在原则上适用于任何纠缠措施，在这里，我们提供了明确的价值观的纠缠和广义并发的几何措施。
We present a full definition of mixed maximally entangled (MME) states for multipartite systems, generalizing their existing definition for bipartite systems by using multipartite Schmidt decomposition. MME states are a special kind of maximally entangled mixed state (MEMS) for which every pure decomposition state in all decompositions is maximally entangled. Thus, MME states have entanglement 1 by all valid unit-normalized entanglement measures, whereas general MEMS can have entanglement less than 1. Multipartite MME states likely have important applications such as remote state preparation, …
我们通过几个纠缠单调来研究是否所有的最大纠缠态都是纯的。在两体情况下，我们发现导致纠缠熵作为纠缠度量的唯一性的相同条件，排除了最大混合纠缠态的存在。在多体情况下，我们的结论使我们能够推广一夫一妻的纠缠的想法：我们建立了\textit{polygamy of entanglement}，表示如果一个一般的状态是最大的纠缠相对于某种多体纠缠，那么它必然是任何其他系统的因式分解。
Complete complementarity relations, as e.g. $P(ρ_{A})^{2} + C(ρ_{A})^{2} + E(|Ψ\rangle_{AB})^{2}=1$, constrain the local predictability, $P$, and local coherence, $C$, and the entanglement, $E$, of bipartite pure states. For pairs of qubits prepared initially in a particular class of partially entangled pure states with null local coherence, these relations were used in Ref. [Phys. Lett. A, 451, 128414 (2022)] to provide an operational connection between local predictability of the pre-measurement states with the probability of the maximally entangled components of the states after the Bell-ba…
Entanglement of genuinely entangled subspaces and states: exact, approximate, and numerical results
量子纠缠子空间（GES）是多体希尔伯特空间的子空间，只由真正的多方纠缠纯态组成。它们是著名的完全纠缠子空间概念的自然推广，根据定义，完全纠缠子空间没有完全乘积向量。纠缠子空间是量子信息理论的重要工具，因为它们直接导致纠缠态的构造，因为在这样的子空间上支持的任何状态都是自动纠缠的。此外，它们在量子纠错领域也被证明是有用的。在我们最近的贡献[M。Demianowicz和R. Augusiak，Phys. Rev. A \textbf{98}，012313（2018）]，我们已经定性地研究了GES与所谓的非正交不可扩展乘积基的关系，并提供了这样的子空间的一些构造。本工作的主要目的是对GES的纠缠特性进行定量研究。首先，我们展示了如何可以尝试计算解析的子空间纠缠，定义为纠缠的最小纠缠矢量从子空间，GES和说明我们的方法，将其应用到一类新的GES。其次，我们表明，某些半定规划松弛可以利用估计的GES纠缠和应用这一观察到的几类GES揭示，在许多情况下，该方法提供了准确的结果。最后，我们研究了GES上某些态的纠缠度，并与相应子空间的纠缠度进行了比较，发现了几种GES的白噪声鲁棒性。在我们的研究中，我们使用（广义）几何测度作为量子纠缠的量词。
