Abstract

Using the complementary wavelike and particlelike natures of photons, one can make “interaction-free” measurements (IFM)–the presence of an object can be determined with no photons being absorbed. By using an application of the quantum zeno effect (weakly and repeatedly testing for the object’s presence so that the otherwise coherent evolution of the interrogating photon is inhibited), we have demonstrated the feasibility of IFMs with an efficiency of >85%,¹ higher than that possible in the original IFM scheme, where, at most, half of the measurements could be interaction free.² We also investigate various interaction-free imaging systems, demonstrate imaging with a resolution <5 μm, and define the limits to these systems. We also discuss in which sense interaction-free measurements really are not.

© 1998 Optical Society of America