Figure 3
From: Quantum interferometry with three-dimensional geometry
(a) Comparison of the QFIs for the N = 2, N = 3, N = 4 interferometers fed with a Fock state 
a coherent state with an external phase reference beam 
and a coherent state without an external phase reference beam 
.(b)–(c) QFI 
and FI 
for (b) a 3-modes interferometer with a 
input state and (c) for a 4-modes interferometer with an input 
state. The optimal working points are obtained when 
.
