“…The degree of this amplification can be quantified by the so-called weak value defined as , where and are the pre-and post-selection states of the QS. When these two state vectors are (nearly) orthogonal, and their overlapping is small, the weak value can significantly exceed the normal eigenvalue and lead to an amplified meter shift to overcome certain environmental disturbances [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Specifically, the ultra-small transversal shift of a beam can be observed when WVA is introduced [ 10 , 11 ], and the longitudinal optical phase can be precisely measured when an imaginary weak value is explored [ 12 , 13 ]; what is more, the optical Kerr effect in a single-photon level can also be amplified through WVA [ 14 ].…”