We discuss quantum fluctuation in excited states （named thermo number states） of mesoscopic LC circuits at a finite temperature. By introducing the coherent thermo state into the thermo field dynamics pioneered by Umezawa and using the natural representation of thermo squeezing operator we can concisely derive the fluctuation. The result shows that the noise becomes larger when either temperature or the excitation number increases.
The new generalized coherent-entangled state representation |α, p μ,ν is successfully derived via constructing the integration of unity in normally ordered Gaussian operator forms and then decomposing it as projection operators. This is a convenient approach for obtaining new representations. We then prove that |α, p μ,ν has the completeness relation and only partly orthogonal, then discuss how to use a beamsplitter to produce such a state. As its potential application, formulas can be obtained by using the completeness of |α, p μ,ν , which is very important in mathematical physics, especially in quantum optics.
