Entangled two-photon source using biexciton emission of an asymmetric quantum dot in a cavity
Entangled two-photon source using biexciton emission of an asymmetric quantum dot in a cavity
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DOI：
10.1103/physrevb.67.085317
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发表时间：
2003-02-15
影响因子：
3.7
通讯作者：
Barnes, CHW
中科院分区：
文献类型：
--
作者：
Stace, TM;Milburn, GJ;Barnes, CHW
提出了一种利用量子点中电泵浦双激子辐射衰变产生纠缠光子对的半导体方案。对称点产生偏振纠缠，但实验实现的非对称点产生的光子在偏振和频率上都纠缠。在这项工作中，我们研究了擦除包含在非对称量子点产生的光子的频率中的“哪条路径”信息以恢复偏振纠缠光子的可能性。本文研究了在简并腔模对接近于非简并激子跃迁频率的泄漏光腔中，具有非简并中间激子态的双激子。利用开放量子系统方法计算了双光子态从腔中逃逸后的偏振纠缠，并通过双光子干涉条纹的可见度来度量。我们明确地将双光子可见性与Bell不等式违反的程度联系起来，推导出一个将观察到Bell不等式违反的阈值。我们的结果表明，一个理想的腔将产生最大的偏振纠缠的光子对，甚至一个非理想的腔将产生部分纠缠的光子对能够违反贝尔不等式。
A semiconductor based scheme has been proposed for generating entangled photon pairs from the radiative decay of an electrically pumped biexciton in a quantum dot. Symmetric dots produce polarization entanglement, but experimentally realized asymmetric dots produce photons entangled in both polarization and frequency. In this work, we investigate the possibility of erasing the "which-path" information contained in the frequencies of the photons produced by asymmetric quantum dots to recover polarization-entangled photons. We consider a biexciton with nondegenerate intermediate excitonic states in a leaky optical cavity with pairs of degenerate cavity modes close to the nondegenerate exciton transition frequencies. An open quantum system approach is used to compute the polarization entanglement of the two-photon state after it escapes from the cavity, measured by the visibility of two-photon interference fringes. We explicitly relate the two-photon visibility to the degree of the Bell-inequality violation, deriving a threshold at which Bell-inequality violations will be observed. Our results show that an ideal cavity will produce maximally polarization-entangled photon pairs, and even a nonideal cavity will produce partially entangled photon pairs capable of violating a Bell-inequality.