从平衡态全息超导到非平衡态全息超导的研究

To understand the microscopic origin and the non-equilibrium relaxation process of high temperature superconductors is important in both theory and application. High temperature superconductors are strongly coupled systems which makes the conventional method difficult to treat above problems. Fortunately, AdS/CFT duality provides us a powerful tool to study the thermodynamic properties of equilibrium state and the relaxation process far from equilibrium. The realistic materials admit complicated phase structure. The competition and coexistence of different order parameters contribute to the phase transition. In this project, we will analyze these aspects with the holographic method in order to give some insights from gravity side. Explicitly, we will study the zero temperature ground state, the coexisting phase and the entanglement entropy from equilibrium holographic superconductors to unequilibrium holographic superconductors. Studying the condensation and the competition mechanism in superconductor can make us understand some phenomena in condensed matter experiment. The calculation of the entanglement entropy can tell us that weather it is still a probe for predicting phase transition or not in above complicated systems.

高温超导体是一个强耦合系统。高温超导的微观起源及其非平衡态弛豫过程是长期以来公开的科学难题。利用AdS/CFT全息对偶，我们不仅可以通过经典引力理论来研究强耦合系统的热力学性质，还可以用来考察体系远离平衡态后的整个时间演化过程。现实中很多超导体存在丰富的相结构和多重有序态之间的关联与竞争。本项目将对超导相变、多序参量共存与竞争和体系纠缠熵等在平衡态和非平衡态弛豫过程中的行为做深入系统的研究。这些研究结果将为凝聚态物理中的超导相变机制等提供新的理解，在AdS/CFT理论方面检验纠缠熵能否继续作为相变的指针。

利用AdS/CFT全息对偶，我们可以通过经典引力理论来研究强耦合系统的热力学性质。本项目利用全息对偶，对全息纠缠熵、全息热化、多序参量共存与竞争等问题进行了深入研究。相关结果表明：全息纠缠熵的相结构类似于热熵的相结构。这个结论不依赖于边界处时空体积的选择。我们将研究推广到非局域量，表明非局域量的相结构与是热熵标志的相变相同，该结论与场论边界区域的大小无关。这些研究结果将为凝聚态物理中的超导相变机制等提供新的理解，在AdS/CFT理论方面检验纠缠熵能否继续作为相变的指针。