Spontaneous Photon Production in Time-Dependent Epsilon-Near-Zero Materials.
Spontaneous Photon Production in Time-Dependent Epsilon-Near-Zero Materials.
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DOI：
10.1103/physrevlett.118.133904
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发表时间：
2017-02
影响因子：
8.6
通讯作者：
Angus Prain;S. Vezzoli;N. Westerberg;T. Roger;D. Faccio
中科院分区：
文献类型：
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作者：
Angus Prain;S. Vezzoli;N. Westerberg;T. Roger;D. Faccio
量子场论预测，空间均匀但时间变化的介质将从真空状态激发光子对。然而，由于难以实现介质中所需的非绝热和大幅度变化，这一重要的理论预测缺乏实验验证。最近的工作表明，在ε近零（ENZ）材料中，可以在飞秒时间尺度上以光学方式引起统一量级的折射率变化。通过研究空间均匀、时变 ENZ 介质的量子场论，我们从理论上预测光子对的产生比非 ENZ 时变材料大几个数量级。我们还发现，虽然在标准材料中，发射光谱取决于扰动的时间尺度，但在 ENZ 材料中，发射总是在 ENZ 波长处达到峰值。这些研究为从时变背景中观察光子对发射在技术上可行铺平了道路，其对凝聚态物质系统之外的量子场论的影响以及作为新的纠缠光光源的潜在应用。
Quantum field theory predicts that a spatially homogeneous but temporally varying medium will excite photon pairs out of the vacuum state. However, this important theoretical prediction lacks experimental verification due to the difficulty in attaining the required nonadiabatic and large amplitude changes in the medium. Recent work has shown that in epsilon-near-zero (ENZ) materials it is possible to optically induce changes of the refractive index of the order of unity, in femtosecond time scales. By studying the quantum field theory of a spatially homogeneous, time-varying ENZ medium, we theoretically predict photon-pair production that is up to several orders of magnitude larger than in non-ENZ time-varying materials. We also find that while in standard materials the emission spectrum depends on the time scale of the perturbation, in ENZ materials the emission is always peaked at the ENZ wavelength. These studies pave the way to technologically feasible observation of photon-pair emission from a time-varying background with implications for quantum field theories beyond condensed matter systems and with potential applications as a new source of entangled light.