From strong to weak temperature dependence of the two-photon entanglement resulting from the biexciton cascade inside a cavity

Article

关键词: REDUCED DENSITY-MATRICES;    QUANTUM TIME EVOLUTION;    TENSOR PROPAGATOR;    PHOTONS;    DOT;   

DOI  :  10.1103/PhysRevB.99.245301

来源: SCIE

【 摘 要 】

We investigate the degree of entanglement quantified by the concurrence of photon pairs that are simultaneously emitted in the biexciton-exciton cascade from a quantum dot in a cavity. Four dot-cavity configurations are compared that differ with respect to the detuning between the cavity modes and the quantum dot transitions, corresponding to different relative weights of direct two-photon and sequential single-photon processes. The dependence of the entanglement on the exciton fine-structure splitting delta is found to be significantly different for each of the four configurations. For a finite splitting and low temperatures, the highest entanglement is found when the cavity modes are in resonance with the two-photon transition between the biexciton and the ground state and, in addition, the biexciton has a finite binding energy of a few meV. However, this widely used configuration is rather strongly affected by phonons such that other dot-cavity configurations, that are commonly regarded as less suited for obtaining high degrees of entanglement, become more favorable already at temperatures on the order of 10 K and above. If the cavity modes are kept in resonance with one of the exciton-to-ground-state transitions and the biexciton binding energy is finite, the entanglement drastically drops for positive delta with rising temperatures when T is below similar or equal to 4 K, but is virtually independent of the temperature for higher T.

【 授权许可】

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