Some factors of 2 and 4 are incorrect in the previously published version of this paper.

On page 4, in the line below equation (15), and on page 8, in the line below equation (26), the factor 2Γ_A (2Γ_B) should be replaced by Γ_A (Γ_B).

On page 5, just below equation (16), the in-text equations should now read as:

Here τ = Γt and Ω₁ = [(2v/Γ)² - 1]^1/2.

In figure 5, the label on the x-axis should be Γt and in the caption to this figure v/4Γ should be replaced by v/Γ.

These corrections do not affect the conclusions of the paper.