Sum squeezing of the field amplitude is studied in the nondegenerate and degenerate frequency upconversion process under the short interaction time. It is shown that sum squeezing can be converted into normal squeezing via sum-frequency generation in the nondegenerate frequency upconversion process, while the amplitude-squared squeezing of the fundamental mode directly changed into the squeezing of the harmonic in the degenerate frequency upconversion process. All reachable conditions of uncorrelated modes for obtaining a sum squeezing in two modes and its dependence on the squeezing of individual field modes are investigated. It is found that the squeezed states are associated with large number of pump photons. It is also confirmed that the higher-order squeezing (sum squeezing) is directly associated with coupling of the field and interaction time.

中文翻译：

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频率上变频过程中场振幅的总压缩

在短时间交互作用下，在非退化和退化频率上变频过程中研究了场振幅的求和压缩。结果表明，在非简并频率上变频过程中，可以通过和频产生将总和挤压转换为普通挤压，而在简并频率上变频过程中，基本模的振幅平方挤压直接变为谐波的挤压。研究了不相关模式的所有可达条件，以得到两种模式的总和压缩及其对各个场模式的压缩的依赖性。发现挤压状态与大量的泵浦光子有关。