Di Piazza A, Wistisen T N, Tamburini M, Uggerhøj U I
Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, D-69117 Heidelberg, Germany.
Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus, Denmark.
Phys Rev Lett. 2020 Jan 31;124(4):044801. doi: 10.1103/PhysRevLett.124.044801.
Processes occurring in the strong field regime of QED are characterized by background electromagnetic fields of the order of the critical field F_{cr}=m^{2}c^{3}/ℏ|e| in the rest frame of participating charges. It has been conjectured that if in their rest frame electrons and positrons experience field strengths of the order of F_{cr}/α^{3/2}≈1600F_{cr}, with α≈1/137 being the fine-structure constant, their effective coupling with radiation becomes of the order of unity. Here we show that channeling radiation by ultrarelativistic electrons with energies of the order of a few TeV on thin tungsten crystals allows us to test the predictions of QED close to this fully nonperturbative regime by measuring the angularly resolved single photon intensity spectrum. The proposed setup features the unique characteristics that essentially all electrons (1) undergo at most a single photon emission and (2) experience at the moment of emission and in the angular region of interest the maximum allowed value of the field strength, which at 2 TeV exceeds F_{cr} by more than 2 orders of magnitude in their rest frame.
量子电动力学强场 regime 中发生的过程，其特征是在参与电荷的静止参考系中，背景电磁场的强度达到临界场 (F_{cr}=m^{2}c^{3}/\hbar|e|)。据推测，如果在其静止参考系中，电子和正电子经历的场强达到 (F_{cr}/α^{3/2}≈1600F_{cr})（其中 (α≈1/137) 是精细结构常数），那么它们与辐射的有效耦合将达到单位量级。在此，我们表明，能量约为几太电子伏特的超相对论电子在薄钨晶体上产生的沟道辐射，使我们能够通过测量角度分辨的单光子强度谱，来检验接近这个完全非微扰 regime 的量子电动力学预测。所提议的装置具有独特的特性，即基本上所有电子（1）最多经历一次单光子发射，并且（2）在发射时刻以及在感兴趣的角度区域内，经历场强的最大允许值，在 2 太电子伏特时，该值在其静止参考系中比 (F_{cr}) 超出 2 个以上数量级。
