Pseudo-Hermitian Systems In article number 2000081, Yun Lai, Jie Luo, and co-workers propose an optical analog of quantum field theory of vacuum, where virtual particles are created and annihilated. Based on transformation optics, optical loss and gain are separated in physical space, forming a new class of non-Hermitian systems with unprecedented robustness in energy balance, thus denoted as pseudo-Hermitian systems.