发表机构
Vellore Institute of Technology（维洛尔理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究解析推导了de Sitter时空中Unruh-DeWitt探测器的渐近退相干系数，发现最小耦合场的退相干强于共形耦合场，比值满足1+(H/ω)^2，且差异在小能隙时最显著。
AI 中文摘要
我们研究了在$(1+3)$维de Sitter时空中，一个与无质量实标量场耦合的二能级Unruh--DeWitt探测器的相干性损失。将探测器-场相互作用微扰处理至二阶，我们推导了共形耦合和最小耦合标量场的实渐近退相干衰减系数的解析表达式。对于共形耦合场，该系数在小能隙极限下保持有限，并在大能隙区域随探测器能隙线性增长。对于无质量最小耦合场，Wightman函数的对数部分产生额外的正贡献。这为先前已知的探测器跃迁响应的红外增强提供了到控制探测器相干性的渐近系数的显式解析推广。在本文采用的绝热调节半线处方下，当在固定平均时间和固定正探测器能隙下移除调节器时，显式依赖于平均时间的部分对实非零频率渐近系数没有贡献。该渐近结果并不描述完整的有限时间动力学，后者依赖于开关函数和观测区间。在所陈述的处方内，对于$\omega>0$，系数满足$\Gamma_{\rm MMC}>\Gamma_{\rm CC}$，且$\Gamma_{\rm MMC}/\Gamma_{\rm CC}=1+(H/\omega)^2$。这种差异在小能隙区域最为显著，而对于大探测器能隙，两个系数相互接近。
英文摘要
We investigate the loss of coherence of a two-level Unruh--DeWitt detector coupled to massless real scalar fields in $(1+3)$-dimensional de Sitter spacetime. Treating the detector--field interaction perturbatively to second order, we derive analytic expressions for the real asymptotic coherence-decay coefficients for conformally and minimally coupled scalar fields. For the conformally coupled field, the coefficient remains finite in the small-gap limit and grows linearly with the detector energy gap in the large-gap regime. For the massless minimally coupled field, the logarithmic sector of the Wightman function produces an additional positive contribution. This provides an explicit analytic extension of the previously known infrared enhancement of detector transition responses to the asymptotic coefficient governing detector coherence. The explicitly average-time-dependent sector does not contribute to the real nonzero-frequency asymptotic coefficient under the adiabatically regulated half-line prescription adopted here, when the regulator is removed at fixed average time and fixed positive detector gap. This asymptotic result does not describe the complete finite-time dynamics, which depends on the switching function and observation interval. Within the stated prescription, the coefficients satisfy $Γ_{\rm MMC}>Γ_{\rm CC}$ for $ω>0$, with $Γ_{\rm MMC}/Γ_{\rm CC} =1+(H/ω)^2$. The distinction is most pronounced in the small-gap regime, whereas the two coefficients approach one another for large detector gaps.
Comments18 pages, 2 figures
