| 1. | In the case of type ii down - conversion , the two down - converted photons have orthogonal polarizations
在第ii类下转换情况下，这两个下转换光子是正交偏振的。 |
| 2. | 2 . we measure the down - conversion ring with ccd and analysis the thickness of the down - conversion ring . 3
分析了抽运光的走离效应和群速失配对下转换过程的影响。 |
| 3. | And the spdc has also been widely studied for its entanglement of time , space , polarization , and energy
另外，参量下转换产生的光子对具有时间、空间、偏振、能量等多种纠缠，因而在理论和实验上都得到了广泛的研究。 |
| 4. | In the case of type i down - conversion , the polarization of the signal and the idler photons will be identical , its direction being determined by the polarization of the pump
在第i类下转换情况下，信号光和闲频光的偏振是一样的，它们的方向是由泵浦光的偏振决定的。 |
| 5. | The maximum 50500 photo counts per second with 76mhz pump pulse frequency is detected . the probability to be single - photon state of every count is better than 99 % 5
在抽运光脉冲重复频率为76mhz的情况下，得到了每秒50500次的下转换光子记数，其中单光子概率大干99 。 |
| 6. | We confirm its tuning characteristics by changing crystal ' s temperature in our experiment the wavelength of the opo output can be tuned from 1988nm to 2293nm with the crystal ' s temperature range of 8 degree
然后在实验上利用晶体不同的极化周期，在晶体温度改变8的情况下，得到了波长调谐范围在1988nm - 2293nm的下转换光输出。 |
| 7. | Our approach differs from a recent theoretical paper that dealt with the possible conservation of the combined spin and orbital angular momentum in relation to the susceptibility of the down - conversion crystal
我们的方法与新近一些理论文章提出的方法是不一样的，他们处理自旋角动量和轨道角动量可能的守恒当中涉及到了下转换晶体的磁化系数。 |
| 8. | The effect of pump beam ' s walk - off and the group - velocity - mismatch in bbo crystal is discussed , the group - velocity - mismatch can be compensated by non - collinear phase - match when the angle between signal and idler beams equals to 14 . 4
当下转换光与抽运光夹角达到13 . 4度时，非共线相位匹配基本可以消除晶体中群速失配对下转换过程的影响。 |
| 9. | 3 ) the quantum noise characteristics of the output of tropo are theoretically analyzed and the intensity - diflerence squeezing of two down - conversion beams was experimental obtained . the intensity - difference noise reduction was 0 . 4db
第三章：讨论了三共振光学参量振荡器的量子噪声特性，并实现了两下转换光之间的强度差压缩，压缩度达0 . 4db 。 |
| 10. | Because spdc creates photons in pairs , if one photon is found in one arm of the twin - photon , we know there must exists a single - photon state in another arm . so , we can assure when the single - photon state generate without detecting it
其中，自发参量下转换因其成对的产生下转换光子，可以通过探测其中之一来确认另一个是否为单光子态，这样就可以在不破坏单光子的情况下确认单光子的存在。 |
