A semiconductor source of triggered entangled photon pairs
A semiconductor source of triggered entangled photon pairs
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DOI：
10.1038/nature04446
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发表时间：
2006-01-12
期刊：
影响因子：
64.8
通讯作者：
Shields, AJ
中科院分区：
文献类型：
--
作者：
Stevenson, RM;Young, RJ;Shields, AJ
纠缠光子对是量子光学中的重要资源（1），并且对于量子信息（2）应用（如量子密钥分配（3，4）和受控量子逻辑操作（5））至关重要。量子点中双激子的辐射衰减-即由两个束缚电子-空穴对组成的状态-已被提出作为触发偏振纠缠光子对的来源（6）。然而，迄今为止，实验已经表明，中间激子能量的分裂仅产生经典相关发射（7-9）。在这里，我们展示了触发光子对发射从单量子点暗示的偏振纠缠。我们通过调整分裂为零，通过应用面内磁场或仔细控制生长条件来实现这一点。“按需”产生的纠缠光子对具有优于其他方案（10-13）的显著基本优点，其他方案可能遭受多对发射，或者需要后选择技术或使用光子数鉴别检测器。此外，对生成时间的控制对于将许多量子信息方案扩展到几个门之外是必不可少的。我们的研究结果表明，一个触发纠缠光子对源可以实现一个简单的半导体发光二极管（14）。
Entangled photon pairs are an important resource in quantum optics(1), and are essential for quantum information(2) applications such as quantum key distribution(3,4) and controlled quantum logic operations(5). The radiative decay of biexcitons - that is, states consisting of two bound electron - hole pairs - in a quantum dot has been proposed as a source of triggered polarization-entangled photon pairs(6). To date, however, experiments have indicated that a splitting of the intermediate exciton energy yields only classically correlated emission(7-9). Here we demonstrate triggered photon pair emission from single quantum dots suggestive of polarization entanglement. We achieve this by tuning the splitting to zero, through either application of an in-plane magnetic field or careful control of growth conditions. Entangled photon pairs generated 'on demand' have significant fundamental advantages over other schemes(10-13), which can suffer from multiple pair emission, or require post-selection techniques or the use of photon-number discriminating detectors. Furthermore, control over the pair generation time is essential for scaling many quantum information schemes beyond a few gates. Our results suggest that a triggered entangled photon pair source could be implemented by a simple semiconductor light-emitting diode(14).