标题： 自然线形的规范不变性和二能级原子的耗散动力学 显示英文标题

标题： Gauge invariance of the natural lineshape and dissipative dynamics of a two-level atom

摘要： 激发态两能级原子（TLA）的自然线形计算长期以来被认为与规范有关，某些实验结果与使用偶极规范计算的线形更为一致。 我们表明，通过使用一种符合规范原理的截断库仑规范哈密顿量，可以获得正确的输出谱。 对于由于额外哈密顿量耦合而产生动力学的TLA，我们还表明，在与Born-Markov近似相同的有效条件下，主方程是规范不变的，尽管不同规范具有不同的光谱密度。 这些结果强调了在输入输出理论中使用正确截断的规范不变哈密顿量的重要性，以获得准确的频率依赖谱，即使在弱耦合区域也是如此。 显示英文摘要

摘要： The calculation of the natural lineshape of an excited two-level atom (TLA) has long been known to be gauge-dependent, with certain experiments in better agreement with the lineshape calculated with the dipole gauge. We show that by using a Coulomb gauge Hamiltonian truncated in a manner consistent with the gauge principle, the correct output spectrum can be obtained. For TLAs undergoing dynamics arising from additional Hamiltonian couplings, we also show that the master equation is gauge-invariant under the same conditions of validity as the Born-Markov approximation, despite different gauges having different spectral densities. These results highlight the importance of using correctly truncated gauge-invariant Hamiltonians in input-output theory for accurate frequency-dependent spectra, even in weak coupling regimes.