unitary deterministic
The operator 



U
(
t
)
=

e

−
i
H
t

/

ℏ




{\displaystyle U(t)=e^{-iHt/\hbar }}

 is known as the time-evolution operator, and has the crucial property that it is unitary. This time evolution is deterministic in the sense that – given an initial quantum state 



ψ
(
0
)


{\displaystyle \psi (0)}

  – it makes a definite prediction of what the quantum state 



ψ
(
t
)


{\displaystyle \psi (t)}

 will be at any later time.
