Technische Physik, Physikalisches Institut, and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
Nat Commun. 2013;4:1747. doi: 10.1038/ncomms2764.
Controlled non-local energy and coherence transfer enables light harvesting in photosynthesis and non-local logical operations in quantum computing. This process is intuitively pictured by a pair of mechanical oscillators, coupled by a spring, allowing for a reversible exchange of excitation. On a microscopic level, the most relevant mechanism of coherent coupling of distant quantum bits--like trapped ions, superconducting qubits or excitons confined in semiconductor quantum dots--is coupling via the electromagnetic field. Here we demonstrate the controlled coherent coupling of spatially separated quantum dots via the photon mode of a solid state microresonator using the strong exciton-photon coupling regime. This is enabled by two-dimensional spectroscopy of the sample's coherent response, a sensitive probe of the coherent coupling. The results are quantitatively understood in a rigorous description of the cavity-mediated coupling of the quantum dot excitons. This mechanism can be used, for instance in photonic crystal cavity networks, to enable a long-range, non-local coherent coupling.
受控非局域能量和相干转移使光合作用中的光捕获和量子计算中的非局域逻辑运算成为可能。这个过程可以通过一对机械振荡器直观地表示，它们通过弹簧耦合，允许激发的可逆交换。在微观水平上，最相关的机制是通过电磁场对离域量子比特（如被俘获的离子、超导量子位或半导体量子点中的激子）进行相干耦合。在这里，我们通过使用强激子-光子耦合状态的固态微谐振器的光子模式，演示了通过二维光谱学对样品相干响应的空间分离量子点的受控相干耦合，这是相干耦合的灵敏探针。在对量子点激子的腔介导耦合的严格描述中，可以对结果进行定量理解。这种机制可用于光子晶体腔网络，以实现长程、非局域相干耦合。
