近日，英国沃里克大学的B. Sharmila与巴西乌贝兰迪亚联邦大学的F. M. Souza等人合作并取得一项新进展。经过不懈努力，他们发现库柏对分束器能够作为一种可行的纠缠电子源。相关研究成果已于2024年6月28日在国际知名学术期刊《物理评论A》上发表。

该团队研究了由两个量子点附着的超导体库珀对分束器组成的系统中纠缠电子对的产生。研究人员考虑了三个过程: 交叉安德烈夫反射、共隧穿和库仑相互作用。总之，这些过程在纠缠电子态的形成中起着至关重要的作用，电子处于空间分离的量子点中。通过使用微扰理论，研究人员推导出一个解析有效模型，该模型可以简单地描述纠缠态形成背后的复杂过程。几个纠缠量词，包括量子互信息，负性和并发，被用来验证他们的发现。

最后，他们定义并计算了与两个电子检测相关的协方差，每个电子都来自一个具有特定自旋值的量子点。这一观测值的时间演化遵循所有纠缠量子的动力学，因此表明它可以在量子信息协议的未来应用中成为映射纠缠电子生成的有用工具。

附：英文原文

Title: Cooper-pair beam splitter as a feasible source of entangled electrons

Author: B. Sharmila, F. M. Souza, H. M. Vasconcelos, L. Sanz

Issue&Volume: 2024/06/28

Abstract: We investigate the generation of an entangled electron pair emerging from a system composed of two quantum dots attached to a superconductor Cooper-pair beam splitter. We take into account three processes: crossed Andreev reflection, cotunneling, and Coulomb interaction. Together, these processes play crucial roles in the formation of entangled electronic states, with electrons being in spatially separated quantum dots. By using perturbation theory, we derive an analytical effective model that allows a simple picture of the intricate process behind the formation of the entangled state. Several entanglement quantifiers, including quantum mutual information, negativity, and concurrence, are employed to validate our findings. Finally, we define and calculate the covariance associated with the detection of two electrons, each originating from one of the quantum dots with a specific spin value. The time evolution of this observable follows the dynamics of all entanglement quantifiers, thus suggesting that it can be a useful tool for mapping the creation of entangled electrons in future applications within quantum information protocols.

DOI: 10.1103/PhysRevA.109.062439

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.062439