光与原子纠缠存储寿命与磁场噪声关系的实验研究

在冷原子系综中,利用自发拉曼散射过程产生光与原子纠缠,测量了恢复效率随存储时间的关系。实验结果显示在没有施加轴向磁场时的存储寿命仅仅只有40μs。而在施加轴向磁场的情况下,存储时间在50μs以后甚至在400μs时都可以测量到明显的恢复信号,存储寿命明显高于100μs,远高于未施加轴向磁场时的情况。对这个实验现象进行分析认为:原子所处的环境中存在磁场噪声的影响,当没有轴向磁场时,噪声会扰乱自旋波信号的相位;当有轴向磁场时,磁场噪声对自旋波相位的影响便被抑制了。

Experimental Observation of Magnetic Field Noise in Quantum Memory

In the cold atom ensemble,wtih the generation of quantum memory by SRS(Spontaneous Raman Scattering)procession,we measured the retrieval efficiency over time in different magnetic fields.The experimental results showed that the storage life was only 40μs in the case of zero magnetic field.When we applied an axial magnetic field,retrieval signal could be significantly measured after 50μs or even 400μs.Storage life was above 100μs,much higher than that when no axial magnetic field was applied.The analysis of this experimental phenomenon showed that there is on of magnetic field noise in the cold atom ensemble.When there is no axial magnetic field,the noise disturbs the phase of the spin wave;When there is an axial magnetic field,the effect of magnetic field noise on the phase of spin wave is suppressed.