Two-photon coherent states of the radiation field

Horace P. Yuen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1935 Scopus citations


The concept of a two-photon coherent state is introduced for applications in quantum optics. It is a simple generalization of the well-known minimum-uncertainty wave packets. The detailed properties of two-photon coherent states are developed and distinguished from ordinary coherent states. These two-photon coherent states are mathematically generated from coherent states through unitary operators associated with quadratic Hamiltonians. Physically they are the radiation states of ideal two-photon lasers operating far above threshold, according to the self-consistent-field approximation. The mean-square quantum noise behavior of these states, which is basically the same as those of minimum-uncertainty states, leads to applications not obtainable from coherent states or one-photon lasers. The essential behavior of two-photon coherent states is unchanged by small losses in the system. The counting rates or distributions these states generate in photocount experiments also reveal their difference from coherent states.

Original languageEnglish (US)
Pages (from-to)2226-2243
Number of pages18
JournalPhysical Review A
Issue number6
StatePublished - 1976

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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