近日，德国马克斯·普朗克物质结构与动力学研究所的I-Te Lu&Angel Rubio及其研究团队取得一项新进展。经过不懈努力，他们基于第一性原理量子电动力学（QEDFT）揭示了MgB₂中的腔增强超导性。相关研究成果已于2024年12月5日在国际知名学术期刊《美国科学院院刊》上发表。

本文从理论上证明，通过腔内的真空电磁场涨落可以影响平衡态基态中声子介导的超导配对。研究人员采用最近发展的从头算量子电动力学密度泛函理论近似方法，具体研究了不同腔设置下MgB₂的声子介导超导行为，并发现在强光-物质耦合状态下，通过光子真空涨落，在平面内（或平面外）极化的实际腔中，其超导转变温度T_c最多可提高约10%。

研究结果强调，在扩展系统中，强光-物质耦合可以通过同时改变电子结构和声子色散，以非微扰的方式深刻改变材料性质。这一发现指出了一条通过腔材料工程在实验上实现平衡态下光控超导的路径。

据悉，强激光脉冲能够调控超导性，通过利用强光与物质的相互作用来诱导非平衡态的瞬时配对。

附：英文原文

Title: Cavity-enhanced superconductivity in MgB₂ from first-principles quantum electrodynamics (QEDFT)

Author: Lu, I-Te, Shin, Dongbin, Svendsen, Mark Kamper, Hübener, Hannes, De Giovannini, Umberto, Latini, Simone, Ruggenthaler, Michael, Rubio, Angel

Issue&Volume: 2024-12-5

Abstract: Strong laser pulses can control superconductivity, inducing nonequilibrium transient pairing by leveraging strong-light matter interaction. Here, we demonstrate theoretically that equilibrium ground-state phonon-mediated superconductive pairing can be affected through the vacuum fluctuating electromagnetic field in a cavity. Using the recently developed ab initio quantum electrodynamical density-functional theory approximation, we specifically investigate the phonon-mediated superconductive behavior of MgB₂ under different cavity setups and find that in the strong light–matter coupling regime its superconducting transition temperature T_c can be enhanced at most by ≈10% in an in-plane (or out-of-plane) polarized and realistic cavity via photon vacuum fluctuations. The results highlight that strong light–matter coupling in extended systems can profoundly alter material properties in a nonperturbative way by modifying their electronic structure and phononic dispersion at the same time. Our findings indicate a pathway to the experimental realization of light-controlled superconductivity in solid-state materials at equilibrium via cavity materials engineering.

DOI: 10.1073/pnas.2415061121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2415061121