Department of Physics, Shanghai Jiaotong University, Shanghai 200030, China; Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Abstract:
Based on thermo field dynamics (TFD) and using the thermo Wigner
operator in the thermo entangled state representation we derive the
Wigner function of number states at finite temperature (named thermo
number states). The figure of Wigner function shows that its shape
gets smoothed as the temperature rises, implying that the quantum
noise becomes larger.