Generation and detection of bright quantum entangled light pulses using adaptive optical pulse control in frequency domain

量子关联是通过超短激光脉冲在光纤中引起的光学非线性而发展起来的。本文着重研究了超短激光脉冲频率模间量子关联的形成，并对光子数压缩的产生和探测进行了实验和理论研究。主要研究结果如下：(1)光脉冲在反常色散区传输光纤时，光谱中心附近的光子数密度之间形成负量子关联。我们从理论上揭示了通过参考输出脉冲的负相关来自适应整形输入激光脉冲的光谱相位，可以显著改善直接对应于光子数压缩的负量子关联。此外，我们还可以利用类似的自适应控制…实现激光脉冲中不同光谱分量之间的双模压缩更多的是我。然而，由于光谱脉冲整形装置的时空耦合效应，其中一些频率分量耦合到光纤上的效率极低，这些都还没有在实验中实现。(2)光子晶体光纤通过自相位调制、受激拉曼散射和四波混频产生超宽带，当中心波长位于光纤零色散波长附近的光脉冲被发射时，斯托克斯拉曼分量使光纤传输光谱向更长的波长移动，并表现出类孤子的性质。我们首次在实验上观察到在斯托克斯拉曼分量处可以获得极高的光子数压缩，从我们的数值分析中可以看出，在宽谱范围内形成了复杂的量子关联。在反斯托克斯分量处也可以获得较高的光子数压缩。(3)由于反斯托克斯脉冲是通过被斯托克斯脉冲捕获来传输光纤的。这种共同传播会在两个脉冲之间产生量子关联。利用这一机制，我们揭示了当具有不同中心频率的两个脉冲可以在一根光纤中一起传输时，可以在这两个脉冲之间建立量子关联。因此，光纤可以作为操控脉冲间量子关联的平台。(4)我们用Er光纤光源产生的1.5μm超短脉冲重复了类似的实验。然而，由于ASE产生了显著的过量噪声，因此无法实现光子数压缩。然而，我们成功地产生了真空态的正交压缩。因此，Er光纤源仍然可以用来产生连续变量的量子纠缠态。较少

Quantum correlation is evolved via optical nonlinearities induced by ultrashort laser pulses in optical fibers. In this study, particular emphasis was placed on the quantum correlation formation among frequency modes of ultrashort laser pulses, and generation and detection of photon-number squeezing was experimentally and theoretically studied. The following results were obtained.(1)When an optical short pulse propagates an optical fiber in the anomalous dispersion regime, negative quantum correlation is formed among photon-number density around the center of spectrum. We have theoretically revealed that the negative quantum correlation, which directly corresponds to photon-number squeezing, can be dramatically improved when the spectral phase of the input laser pulse is adaptively shaped by referring to the negative correlation of the output pulse. Moreover, we can achieve two-mode squeezing among different spectral components in the laser pulse using the similar adaptive control sche … More me. However, these have not been realized in experiments yet because of spatiotemporal coupling effect at a spectral pulse shaping device, where some frequency components couple to the fiber with extremely low efficiency.(2)Ultra-broad spectrum is generated from a photonic crystal fiber via self-phase modulation, stimulated Raman scattering and four-wave mixing when an optical pulse of which center wavelength locates near the zero dispersion wavelength of the fiber is launched The Stokes Raman component propagates the fiber with spectral shift toward longer wavelength and exhibits soliton-like nature. We experimentally observed for the first time that extremely higher photon-number squeezing is obtainable at the Stokes Raman component, From our numerical analysis, complicated quantum correlation is formed in the broad spectrum. Higher photon-number squeezing is also obtainable at anti-Stokes component.(3)Since the anti-Stokes pulse propagates the fiber by being trapped by the Stokes pulses. Such co-propagation generates quantum correlation between two pulses. Using this mechanism, we revealed that quantum correlation can construct between two pulses with different center frequency when the two pulse can propagate together in a fiber. Therefore, the fiber could be a platform to manipulate quantum correlation among pulses.(4)We repeated the similar experiments with 1.5μm ultrashort pulses generated by an Er-fiber laser source. However, due to significant excess noise caused by ASE, photon-number squeezing cannot be attained. However, we succeeded to generate quadrature squeezing with vacuum state. Therefore, Er fiber sources are still useful to generate quantum entangled state with continuous variable. Less