Let a, b and λ be positive real numbers. Suppose P is an end point of the latus rectum of the parabola y² = 4λx, and suppose the ellipse x²/a² + y²/b² = 1 passes through the point P. If the tangents to the parabola and the ellipse at the point P are perpendicular to each other, then the eccentricity of the ellipse is