近日，法国巴黎高等师范学院物理实验室的B.Plaais课题组发现了石墨烯中的介观Klein-Schwinger效应。相关研究成果已于2023年3月9日在国际学术期刊《自然—物理学》上发表。

该课题组研究了石墨烯中施翁格（Schwinger）效应的介观变体，它容纳着具有近似电子空穴对称的狄拉克费米子。利用输运测量，研究人员报道了弹道石墨烯晶体管夹断处的通用一维施翁格电导。强夹断电场集中在距离晶体管漏极约1μm的范围内，在饱和时诱导施翁格电子-空穴对的产生。这种效应先于对欧姆Zener区的集体不稳定性，长器件中则会在两倍夹断电压处被排除。这些发现有助于我们更好地理解石墨烯中电流饱和极限的限制，并为实验室中进一步的量子电动力学实验提供了方向。

据介绍，粒子-反粒子对产生的强电场湮灭，也称为施翁格效应，是量子电动力学的一种非微扰预测。其实验证明仍然难以实现，因为阈值电场极强，超出了目前的研究范围。

附：英文原文

Title: Mesoscopic Klein-Schwinger effect in graphene

Author: Schmitt, A., Vallet, P., Mele, D., Rosticher, M., Taniguchi, T., Watanabe, K., Bocquillon, E., Fve, G., Berroir, J. M., Voisin, C., Cayssol, J., Goerbig, M. O., Troost, J., Baudin, E., Plaais, B.

Issue&Volume: 2023-03-09

Abstract: Strong electric field annihilation by particle–antiparticle pair creation, also known as the Schwinger effect, is a non-perturbative prediction of quantum electrodynamics. Its experimental demonstration remains elusive, as threshold electric fields are extremely strong and beyond current reach. Here, we propose a mesoscopic variant of the Schwinger effect in graphene, which hosts Dirac fermions with an approximate electron–hole symmetry. Using transport measurements, we report on universal one-dimensional Schwinger conductance at the pinchoff of ballistic graphene transistors. Strong pinchoff electric fields are concentrated within approximately 1μm of the transistor’s drain and induce Schwinger electron–hole pair creation at saturation. This effect precedes a collective instability towards an ohmic Zener regime, which is rejected at twice the pinchoff voltage in long devices. These observations advance our understanding of current saturation limits in ballistic graphene and provide a direction for further quantum electrodynamic experiments in the laboratory.

DOI: 10.1038/s41567-023-01978-9

Source: https://www.nature.com/articles/s41567-023-01978-9