Complementarity and light modes

Abstract

In quantum physics we are confronted with new entities which consist indivisible of an energy packet and a coupled wave. The complementarity principle for certain properties of these quantum objects may be their main mystery. Photons are especially useful to investigate these complementary properties. A series of new experiments using spontaneous parametric down conversion (SPDC) as a tool allowed the detailed analysis of the physical background of this complementarity and offers a new conceptual perspective. Based on these results a straightforward explanation of these sometimes counter-intuitive effects is given.

A novel delayed-choice experimental proposal testing local decisions

“…It is noteworthy that although in this experimental setup a single pair of photons is created, this pair is in a coherent superposition of originating from the first and second non-linear crystal. Coherence is induced by the pumping laser [14,15,16].…”

“…In the 1980's and 1990's, Mandel's group proposed and performed ground-breaking experiments involving two non-linear crystals. In such an experiment [14,15], "phase memory" of the pump beam implied an "induced coherence" between the two crystals: although the process of SPDC is random, coherence can be induced [16]. A follow-up proposal by Ou [17] showed how this type of experiment can be extended into a quantum eraser [18,19].…”