Test of the all-optical control of wave-particle duality of cavity photons by ordinary photodetection.

The principle of complementarity refers to the ability of quantum entities to behave as particles or waves under different experimental conditions. We present a proposal for the experimental observation of the ultrafast all-optical control of the wave-particle duality of light. The device is constituted by a three-level quantum emitter strongly coupled to a microcavity (MC) and can be realized by exploiting a great variety of systems, ranging from atomic physics and semiconductor quantum dots to intersubband polaritons and Cooper pair boxes. The wavelike or particlelike behavior of MC photons can be probed by simply measuring the cavity output photon rate after excitation with pairs of phase-locked weak pulses with precise arrival times.