Journal Title

Physical Review A

Publication Date



We investigate the disturbance of the state of a quantum system in a protective measurement for finite measurement times and different choices of the time-dependent system-apparatus coupling function. The ability to minimize this state disturbance is essential to protective measurement. We show that for a coupling strength that remains constant during the measurement interaction of duration T, the state disturbance scales as T−2, while a simple smoothing of the coupling function significantly improves the scaling behavior to T−6. We also prove that the shift of the apparatus pointer in the course of a protective measurement is independent of the particular time dependence of the coupling function, suggesting that the guiding principle for choosing the coupling function should be the minimization of the state disturbance. Our results illuminate the dynamics of protective measurement under realistic circumstances and may aid in the experimental realization of such measurements.


Quantum Physics; Quantum theory

Publication Information

Physical Review A, 2014, Volume 90, Issue 5, 1-14.

© 2014 American Physical Society

Archived version is the final published version.





Document Type

Journal Article

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Physics Commons