Direct sampling of electric-field vacuum fluctuations
Direct sampling of electric-field vacuum fluctuations
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DOI：
10.1126/science.aac9788
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发表时间：
2015-10-23
期刊：
影响因子：
56.9
通讯作者：
Leitenstorfer, A.
中科院分区：
文献类型：
--
作者：
Riek, C.;Seletskiy, D. V.;Leitenstorfer, A.
量子系统的基态以零点运动为特征。这种以真空波动的形式出现的运动，通常被认为是一种难以捉摸的现象，只是间接地表现出来。在这里，我们报道了对自由空间中电磁辐射真空涨落的直接探测。基态电场变化与四维时空体积成反比，我们用持续几飞秒的紧聚焦激光脉冲对其进行电光采样。亚周期时间读出和远离共振的非线性耦合提供来自纯虚光子的信号，而不需要放大。我们的发现为量子物理提供了一种极端的时间域方法，可以无损地获取光的量子态。这种技术在多太赫兹频率下工作，也可能允许对凝聚态物质中基本激发的本征涨落进行时间分辨研究。
The ground state of quantum systems is characterized by zero-point motion. This motion, in the form of vacuum fluctuations, is generally considered to be an elusive phenomenon that manifests itself only indirectly. Here, we report direct detection of the vacuum fluctuations of electromagnetic radiation in free space. The ground-state electric-field variance is inversely proportional to the four-dimensional space-time volume, which we sampled electro-optically with tightly focused laser pulses lasting a few femtoseconds. Subcycle temporal readout and nonlinear coupling far from resonance provide signals from purely virtual photons without amplification. Our findings enable an extreme time-domain approach to quantum physics, with nondestructive access to the quantum state of light. Operating at multiterahertz frequencies, such techniques might also allow time-resolved studies of intrinsic fluctuations of elementary excitations in condensed matter.