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arXiv 1811.12232quant-phcond-mat.str-elphysics.optics
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等离子体耦合量子点量子比特纠缠态的光学检测与存储

Optical Detection and Storage of Entanglement in Plasmonically Coupled Quantum Dot Qubits

M. Otten, S. K. Gray, G. V. Kolmakov

摘要:

量子模拟、量子密码学和量子通信的最新提议和进展实质上依赖于量子纠缠的形成。与耗散破坏量子相干性的传统观点相反,与耗散环境耦合也可以产生纠缠。我们考虑一个由两个量子点量子比特组成的系统,量子比特与一个共同的阻尼表面等离子体模式耦合,每个量子点也耦合到一个单独的光子腔模式。腔量子电动力学计算表明,在飞秒激光脉冲的光激发下,量子点激子发生纠缠,腔光子的$g^{(2)}$对关联函数的时间演化是纠缠的一个指标.我们还证明了纠缠度在系统的时间演化过程中是守恒的。此外,如果光子腔和量子点模的耦合足够大,则量子点纠缠可以转移到腔模以增加总纠缠寿命。后一种现象可以被看作是纠缠的、长寿命的量子点激子-极化激元形成的标志。在腔/量子点相互作用的强耦合极限下,纠缠的保持为高质量光学腔中纠缠的存储和操纵提供了一种新的手段.

英文摘要:

Recent proposals and advances in quantum simulations, quantum cryptography and quantum communications substantially rely on quantum entanglement formation. Contrary to the conventional wisdom that dissipation destroys quantum coherence, coupling with a dissipative environment can also generate entanglement. We consider a system composed of two quantum dot qubits coupled with a common, damped surface plasmon mode; each quantum dot is also coupled to a separate photonic cavity mode. Cavity quantum electrodynamics calculations show that upon optical excitation by a femtosecond laser pulse, entanglement of the quantum dot excitons occurs, and the time evolution of the $g^{(2)}$ pair correlation function of the cavity photons is an indicator of the entanglement. We also show that the degree of entanglement is conserved during the time evolution of the system. Furthermore, if coupling of the photonic cavity and quantum dot modes is large enough, the quantum dot entanglement can be transferred to the cavity modes to increase the overall entanglement lifetime. This latter phenomenon can be viewed as a signature of entangled, long-lived quantum dot exciton-polariton formation. The preservation of total entanglement in the strong coupling limit of the cavity/quantum dot interactions suggests a novel means of entanglement storage and manipulation in high-quality optical cavities.

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