It is pointed out that a method recently described by Hillery and Zubairy can be generalized to yield the multitime correlation function in any order for an interacting quantum field in the form of a phase-space average. The correlations are expressible as c-number integrals with the help of the coherent-state propagator, but the associated phase-space density is complex. © 1984 The American Physical Society.

Rupamanjari Ghosh

SNU Management

P. Lett

S. Friberg

L. Mandel

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