Eschner J, Raab C, Schmidt-Kaler F, Blatt R
Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
Nature. 2001 Oct 4;413(6855):495-8. doi: 10.1038/35097017.
A single atom emitting single photons is a fundamental source of light. But the characteristics of this light depend strongly on the environment of the atom. For example, if an atom is placed between two mirrors, both the total rate and the spectral composition of the spontaneous emission can be modified. Such effects have been observed using various systems: molecules deposited on mirrors, dye molecules in an optical cavity, an atom beam traversing a two-mirror optical resonator, single atoms traversing a microwave cavity and a single trapped electron. A related and equally fundamental phenomenon is the optical interaction between two atoms of the same kind when their separation is comparable to their emission wavelength. In this situation, light emitted by one atom may be reabsorbed by the other, leading to cooperative processes in the emission. Here we observe these phenomena with high visibility by using one or two single atom(s), a collimating lens and a mirror, and by recording the individual photons scattered by the atom(s). Our experiments highlight the intimate connection between one-atom and two-atom effects, and allow their continuous observation using the same apparatus.
单个发射单光子的原子是光的基本光源。但这种光的特性在很大程度上取决于原子所处的环境。例如，如果将一个原子置于两面镜子之间，自发辐射的总速率和光谱组成都会被改变。利用各种系统都观察到了此类效应：沉积在镜子上的分子、光学腔中的染料分子、穿过双镜光学谐振器的原子束、穿过微波腔的单个原子以及单个俘获电子。当两个同类原子的间距与其发射波长相近时，会出现一种相关且同样基本的现象，即这两个原子之间的光学相互作用。在这种情况下，一个原子发射的光可能会被另一个原子重新吸收，从而导致发射过程中的协同效应。在这里，我们通过使用一个或两个单个原子、一个准直透镜和一面镜子，并记录由原子散射的单个光子，以高可见度观察到了这些现象。我们的实验突出了单原子效应和双原子效应之间的紧密联系，并使得能够使用同一装置对它们进行连续观测。
