Ultrabright source of entangled photon pairs
Ultrabright source of entangled photon pairs
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DOI：
10.1038/nature09148
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发表时间：
2010-07-08
期刊：
影响因子：
64.8
通讯作者：
Senellart, Pascale
中科院分区：
文献类型：
--
作者：
Dousse, Adrien;Suffczynski, Jan;Senellart, Pascale
触发纠缠光子对的源是量子信息科学的关键组成部分（1）;它需要实现线性量子计算（2），纠缠交换（3）和量子隐形传态（4）等功能。偏振纠缠光子对的产生可以通过非线性光学介质中的参数转换（5-7）或通过利用半导体量子点中捕获的两个电子-空穴对的辐射衰减（8-11）来获得。今天，这些光源以非常低的速率工作，每个激发脉冲低于0.01个光子对，这极大地限制了它们的应用。对于基于参数转换的系统，这种低速率本质上是由于源（12）的泊松统计。相反，量子点可以发射具有接近1的概率的单对纠缠光子，但是遭受自然非常低的提取效率。在这里，我们证明了这个缺点可以通过将一个“光子分子”（13）形式的光腔耦合到单个量子点来克服。两个耦合的相同的支柱-光子分子-被蚀刻在半导体平面微腔中，使用光学光刻方法（14），其确保与预选量子点的双激子和激子能量状态的确定性耦合。珀塞尔效应确保了大多数纠缠光子对被发射到两个腔模中，同时提高了两个光学复合路径（15，16）的不可逆性。在第一透镜中收集每个激发脉冲0.12的偏振纠缠光子对速率（具有0.34的并发度）。我们的研究结果开辟了一条通往制造纠缠光子对的固态触发源的道路，总体（创建和收集）效率为80%。
A source of triggered entangled photon pairs is a key component in quantum information science(1); it is needed to implement functions such as linear quantum computation(2), entanglement swapping(3) and quantum teleportation(4). Generation of polarization entangled photon pairs can be obtained through parametric conversion in nonlinear optical media(5-7) or by making use of the radiative decay of two electron-hole pairs trapped in a semiconductor quantum dot(8-11). Today, these sources operate at a very low rate, below 0.01 photon pairs per excitation pulse, which strongly limits their applications. For systems based on parametric conversion, this low rate is intrinsically due to the Poissonian statistics of the source(12). Conversely, a quantum dot can emit a single pair of entangled photons with a probability near unity but suffers from a naturally very low extraction efficiency. Here we show that this drawback can be overcome by coupling an optical cavity in the formof a 'photonic molecule'(13) to a single quantum dot. Two coupled identical pillars-the photonic molecule-were etched in a semiconductor planar microcavity, using an optical lithography method(14) that ensures a deterministic coupling to the biexciton and exciton energy states of a pre-selected quantum dot. The Purcell effect ensures that most entangled photon pairs are emitted into two cavity modes, while improving the indistinguishability of the two optical recombination paths(15,16). A polarization entangled photon pair rate of 0.12 per excitation pulse (with a concurrence of 0.34) is collected in the first lens. Our results open the way towards the fabrication of solid state triggered sources of entangled photon pairs, with an overall (creation and collection) efficiency of 80%.