en عمومى General پژوهشي Research We generalized the squeeze and displacement operators of the one-dimensional harmonic oscillator to the three-dimensional case and based on these operators we construct the corresponding coherent and squeezed states. We have also calculated the Wigner function for the three-dimensional harmonic oscillator and from the analysis of time evolution of this function, the quantum Liouville equation is also presented. Further properties of the quantum states including Mandel’s 􀡽 and quadrature squeezing parameters are discussed as well. Coherent states, Phase space, Squeezed states, Operator algebra. 9 22 http://ijop.ir/browse.php?a_code=A-10-40-1&slc_lang=en&sid=1 Mehdi Miri 10031947532846001079 10031947532846001079 No School of Electrical Engineering, Sharif University of Technology Sina Khorasani sina.khorasani@gmail.com 10031947532846001080 10031947532846001080 Yes School of Electrical Engineering, Sharif University of Technology