Quantum nondemolition measurement
preserves the integrity of the system and the value of the measured observable, which is best thought of as the ideal quantum projective measurement.
Chirkin, "Polarization quantum states of light in nonlinear distributed feedback systems: Quantum nondemolition measurements
of the Stokes parameters of light and atomic angular momentum," Appl.
As a perspective of such an experimental realisation, the combination of quantum logic devices and quantum nondemolition measurements
on a chip are expected (Fushman et al, 2008).