Figure 3
From: Realizing and characterizing chiral photon flow in a circuit quantum electrodynamics necklace
Photon position vector 
and the chiral area S.
The unit vectors 
, 
and 
are assigned to the modes 1, 2 and 3 of the necklace, respectively. The photon position vector is defined as 
with 
and its evolution trace is represented by the dashed line. The chiral area 
is the directed area swept by 
and can be used to characterize the chiral property of the photon flow.
