Weak measurement with light

etection and estimation of Goos-Hanchen and Imbert-Federov shift in light beam by weak value amplification

Light beams, unlike light rays, do not follow laws of reflection of geometrical optics. A light beam reflected from a dielectric surface undergo finite lateral shift (known as Goos-Hanchen shift) and angular shift (known as Imbert-Feverov shift). The later one further depends on polarization of light beam.

The shifts are too tiny to be detected directly. The scheme of weak value amplification was used to detect them.

Quantum measurements, also called strong measurements, are projective i.e. they collapse the state. To avoid this, one can know about the state of a system by weakly coupling it to the measuring device or environment between two strong measurements. Choosing the pre selected and post selected state, the measured value of generalized position (also known as the pointer) anticipated from two strong measurements can be amplified.