Abstract

The uncertainty area (5 (p, q): — [J W(p, q) 2 dp dq] ~ 1 is proposed in place of äp • Öq, and it is shown that each pure quantum state is a minimum uncertainty state in this sense: S (p, q) = 2 n h. For mixed states, on the other hand, d(p, q) > 2nh. In a phase space of 2F(=6N) dimensions, S: = k B • log[<5 f (p, q)/(2nh) F ]with S F (p, q):= [J W(p, q) 2 d pd F q]' 1 is considered as an alternative to von Neumann's entropy S:=k B • trclog~ 1)].