For α, β, z ∈ C and λ>1, if √(λ-1) is the radius of the circle |z-α|^2+|z-β|^2=2 λ, then |α-β| is equal to ____.

For $\displaystyle \alpha, \beta, z \in \mathbb{C}$ and $\displaystyle \lambda>1$, if $\displaystyle \sqrt{\lambda-1}$ is the radius of the circle $\displaystyle |z-\alpha|^2+|z-\beta|^2=2 \lambda$, then $\displaystyle |\alpha-\beta|$ is equal to $\displaystyle \_\_\_\_$.