Akopian N, Lindner N H, Poem E, Berlatzky Y, Avron J, Gershoni D, Gerardot B D, Petroff P M
Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Phys Rev Lett. 2006 Apr 7;96(13):130501. doi: 10.1103/PhysRevLett.96.130501. Epub 2006 Apr 6.
Tomographic analysis demonstrates that the polarization state of pairs of photons emitted from a biexciton decay cascade becomes entangled when spectral filtering is applied. The measured density matrix of the photon pair satisfies the Peres criterion for entanglement by more than 3 standard deviations of the experimental uncertainty and violates Bell's inequality. We show that the spectral filtering erases the "which path" information contained in the photons' color and that the remanent information in the quantum dot degrees of freedom is negligible.
断层扫描分析表明，当应用光谱滤波时，从双激子衰变级联发射的光子对的偏振态会变得纠缠。测量得到的光子对密度矩阵满足纠缠的佩雷斯判据，超出实验不确定性的3个标准差，并且违反了贝尔不等式。我们表明，光谱滤波消除了光子颜色中包含的“哪条路径”信息，并且量子点自由度中的剩余信息可以忽略不计。
