Strong atom-field coupling for Bose-Einstein condensates in an optical cavity on a chip
Strong atom-field coupling for Bose-Einstein condensates in an optical cavity on a chip
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DOI：
10.1038/nature06331
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发表时间：
2007-11-08
期刊：
影响因子：
64.8
通讯作者：
Reichel, Jakob
中科院分区：
文献类型：
--
作者：
Colombe, Yves;Steinmetz, Tilo;Reichel, Jakob
光腔增强了原子与光之间的相互作用，并且相干原子-光子耦合的速率可以大于系统的所有退相干速率。对于单原子，腔量子电动力学(1，2)的这种“强耦合区域”已经成为许多实验进展的主题。人们试图通过捕获(3，4)原子并将其冷却(5，6)到运动基态来控制耦合速率；后者到目前为止已经在一维上实现了(5)。对于多原子系统，三维基态运动通常在原子玻色-爱因斯坦凝聚体(BEC)中实现(7)。尽管最近已经报道了将BEC和光学腔结合在一起的实验(8，9)，但将BEC耦合到单原子处于强耦合区域的腔仍然是一个难以实现的目标。在这里，我们报告了这样一个实验，它是通过将基于光纤的腔(10)与原子芯片技术(11)相结合而实现的。这使得单原子腔量子电动力学实验能够以简化的装置进行，并实现了腔中多个原子的情况，每个原子都相同且强耦合到腔模(12)。此外，BEC可以确定地定位在腔内的任何位置，并且完全定位在驻波腔场的单个反节点内；我们证明了这产生了可控的、可调的耦合率。我们研究了腔传输测量引起的加热速率作为耦合速率的函数，发现对于强耦合的BEC没有可测量的加热。我们在广泛的原子序数和腔原子失谐范围内绘制的耦合原子-腔系统的光谱显示，真空拉比分裂超过20千兆赫，以及意想不到的额外分裂，我们将其归因于原子的超精细结构。我们预计该系统将适合作为量子信息的光-物质量子接口(13)。
An optical cavity enhances the interaction between atoms and light, and the rate of coherent atom-photon coupling can be made larger than all decoherence rates of the system. For single atoms, this 'strong coupling regime' of cavity quantum electrodynamics(1,2) has been the subject of many experimental advances. Efforts have been made to control the coupling rate by trapping(3,4) the atom and cooling(5,6) it towards the motional ground state; the latter has been achieved in one dimension so far(5). For systems of many atoms, the three-dimensional ground state of motion is routinely achieved(7) in atomic Bose-Einstein condensates (BECs). Although experiments combining BECs and optical cavities have been reported recently(8,9), coupling BECs to cavities that are in the strong-coupling regime for single atoms has remained an elusive goal. Here we report such an experiment, made possible by combining a fibre-based cavity(10) with atom-chip technology(11). This enables single-atom cavity quantum electrodynamics experiments with a simplified set-up and realizes the situation of many atoms in a cavity, each of which is identically and strongly coupled to the cavity mode(12). Moreover, the BEC can be positioned deterministically anywhere within the cavity and localized entirely within a single antinode of the standing-wave cavity field; we demonstrate that this gives rise to a controlled, tunable coupling rate. We study the heating rate caused by a cavity transmission measurement as a function of the coupling rate and find no measurable heating for strongly coupled BECs. The spectrum of the coupled atoms-cavity system, which we map out over a wide range of atom numbers and cavity-atom detunings, shows vacuum Rabi splittings exceeding 20 gigahertz, as well as an unpredicted additional splitting, which we attribute to the atomic hyperfine structure. We anticipate that the system will be suitable as a light-matter quantum interface for quantum information(13).