⟨+|ρ(t)|+⟩=12+12cos(ωt).This oscillation is due to the off-diagonal elements of ρ(t), and it is called the coherence of the system (see F...⟨+|ρ(t)|+⟩=12+12cos(ωt).This oscillation is due to the off-diagonal elements of ρ(t), and it is called the coherence of the system (see Fig. This is called decoherence of the system, and the value of γ depends on the physical mechanism that leads to the decoherence. If the state |1⟩ has a larger energy than |0⟩ there may be processes such as spontaneous emission that drive the system to the ground state.
The third postulate states also that after the measurement the system is left in the eigenstate corresponding to the eigenvalue found (more generally, if more than one eigenstate is associated to the ...The third postulate states also that after the measurement the system is left in the eigenstate corresponding to the eigenvalue found (more generally, if more than one eigenstate is associated to the same eigenvalue, the state is projected on the subspace of the eigenvalue an, that is, the subspace spanned by all the eigenstates associated with an).
