Multiple quantum interrogation to determine the position of an object in a serial array of ring resonators

We propose quantum interaction-free measurements to determine not only whether an object exists, but also where it is situated among possible interrogation positions. In the first configuration, the object exists at one of several possible positions, and the other positions are empty. We regard this as multiple quantum trap interrogation. In the second configuration, the object does not exist in any possible interrogation position, but other positions are occupied by objects. We refer to this as multiple quantum loophole interrogation. It is possible to determine the position of a trap or loophole with almost 100% certainty, without any real interaction between the photon and the objects. We performed a preliminary experiment using a serial array of add-drop ring resonators and confirmed that multiple trap and loophole interrogations are possible. We discuss the detuning of resonators from the critical coupling condition, the loss effects in the resonator, the frequency detuning effect of incident light, and the effect of object semitransparency on the interrogation systems.