We investigate the single-photon scattering spectra of a giant atom coupled to a one-dimensional waveguide via multiple connection points or a continuous coupling region. Using a full quantum mechanical method, we obtain the general analytic expressions for the single-photon scattering coefficients, which are valid in both the Markovian and the non-Markovian regimes. We summarize the influences of the nondipole effects, mainly caused by the phases accumulated by photons traveling between coupling points, on the scattering spectra. We find that under the Markovian limit, the phase decay is detuning independent, resulting in Lorentzian line shapes characterized by the Lamb shifts and the effective decay rates, while in the non-Markovian regime, the accumulated phases become detuning dependent, giving rise to non-Lorentzian line shapes, characterized by multiple side peaks and total transmission points. Another interesting phenomenon in the non-Markovian regime is the generation of a broad photonic band gap by a single giant atom. We further generalize the case of discrete coupling points to the continuum limit with atom coupling to the waveguide via a continuous area, and analyze the scattering spectra for some typical distributions of coupling strength.

中文翻译：

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超出偶极子近似的巨原子波导 QED 系统的相干单光子散射光谱

我们研究了通过多个连接点或连续耦合区域耦合到一维波导的巨原子的单光子散射光谱。使用完整的量子力学方法，我们获得了单光子散射系数的一般解析表达式，这在马尔可夫和非马尔可夫状态下均有效。我们总结了非偶极效应对散射光谱的影响，主要由光子在耦合点之间传播所积累的相位引起。我们发现在马尔可夫极限下，相位衰减独立于失谐，导致以兰姆位移和有效衰减率为特征的洛伦兹线形状，而在非马尔可夫范围内，累积相位变得依赖于失谐，从而产生非-洛伦兹线形状，以多侧峰和总传输点为特征。非马尔可夫体系中的另一个有趣现象是单个巨原子产生宽的光子带隙。我们进一步将离散耦合点的情况概括为原子通过连续区域耦合到波导的连续谱极限，并分析了耦合强度的一些典型分布的散射光谱。