Subcycle quantum electrodynamics
Subcycle quantum electrodynamics
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DOI：
10.1038/nature21024
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发表时间：
2017-01-19
期刊：
影响因子：
64.8
通讯作者：
Leitenstorfer, A.
中科院分区：
文献类型：
--
作者：
Riek, C.;Sulzer, P.;Leitenstorfer, A.
电磁辐射的压缩态（1-4）具有低于真空场的量子涨落。它们为量子信息系统（5）和精密计量学（6）提供了独特的资源，包括引力波探测器，这需要前所未有的灵敏度（7）。自从第一次对这种非经典形式的光进行实验以来（8，9），量子分析一直基于零差技术和光子相关测量（10，11）。这些方法目前在可见光到近红外和微波（12）光谱范围内起作用。它们需要一个明确定义的载波频率，并且包含在量子态中的光子需要被吸收或放大。可以进行量子非破坏实验（13，14）以避免在一个正交中的测量的影响，但是该过程以另一正交中的增加的不确定性为代价。在这里，我们产生压缩真空噪声的中红外时间锁定模式。通过自由空间传播后，电场的量子涨落在时域中使用电光采样与几个飞秒激光脉冲（15，16）进行了研究。我们直接比较本地噪声振幅裸（即，未扰动）真空。我们的非线性方法工作的共振，不像零差或光子相关技术，没有吸收或放大的领域，调查。我们发现子周期间隔的噪音水平，大大低于真空场的振幅。因此，由于海森堡的不确定性原理，在相邻的时间间隔内存在增强的波动，这表明产生了高度相关的量子辐射。与远红外（17，18）的努力一起，这项工作使得在真空和热背景条件之间的边界处的能量范围内的光和物质的基本量子动力学的研究成为可能。
Squeezed states(1-4) of electromagnetic radiation have quantum fluctuations below those of the vacuum field. They offer a unique resource for quantum information systems(5) and precision metrology(6), including gravitational wave detectors, which require unprecedented sensitivity(7). Since the first experiments on this non-classical form of light(8,9), quantum analysis has been based on homodyning techniques and photon correlation measurements(10,11). These methods currently function in the visible to near-infrared and microwave(12) spectral ranges. They require a well-defined carrier frequency, and photons contained in a quantum state need to be absorbed or amplified. Quantum non-demolition experiments(13,14) may be performed to avoid the influence of a measurement in one quadrature, but this procedure comes at the expense of increased uncertainty in another quadrature. Here we generate mid-infrared time-locked patterns of squeezed vacuum noise. After propagation through free space, the quantum fluctuations of the electric field are studied in the time domain using electro-optic sampling with few-femtosecond laser pulses(15,16). We directly compare the local noise amplitude to that of bare (that is, unperturbed) vacuum. Our nonlinear approach operates off resonance and, unlike homodyning or photon correlation techniques, without absorption or amplification of the field that is investigated. We find subcycle intervals with noise levels that are substantially less than the amplitude of the vacuum field. As a consequence, there are enhanced fluctuations in adjacent time intervals, owing to Heisenberg's uncertainty principle, which indicate generation of highly correlated quantum radiation. Together with efforts in the far infrared(17,18), this work enables the study of elementary quantum dynamics of light and matter in an energy range at the boundary between vacuum and thermal background conditions.