We introduce a new state representation \eta] for thermal field dynami
cs, which possesses orthonormal and completeness relations. The therma
l operator, which engenders the transition from zero temperature to fi
nite temperature, is shown to have a natural representation in the rep
resentation manifestly exhibiting squeezing. The relationship between
temperature evolution dynamics and the squeezing is also discussed. (C
) 1998 Elsevier Science B.V.