One-Parameter Squeezed Gaussian States of Time-Dependent Harmonic Oscillator and Selection Rule for Vacuum States
نویسندگان
چکیده
By using the invariant method we find one-parameter squeezed Gaussian states for both time-independent and time-dependent oscillators. The squeezing parameter is expressed in terms of energy expectation value for timeindependent case and represents the degree of mixing positive and negative frequency solutions for time-dependent case. A minimum uncertainty proposal is advanced to select uniquely vacuum states at each moment of time. We show that the Gaussian states with minimum uncertainty coincide with the true vacuum state for time-independent oscillator and the Bunch-Davies vacuum for a massive scalar field in a de Sitter spacetime. PACS number(s): 42.50.D; 03.65.G; 03.65.-w Typeset using REVTEX 1
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