Quantum complimentarity, erasers and photons

A recent experiment performed by S. Afshar [first reported by M. Chown, New Scientist {\bf 183}, 30 (2004)] is analyzed. It was claimed that this experiment could be interpreted as a demonstration of a violation of the principle of complementarity in quantum mechanics. Instead, it is shown here that it can be understood in terms of classical wave optics and the standard interpretation of quantum mechanics. Its performance is quantified and it is concluded that the experiment ...

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 of...

In its most orthodox form, Bohr's Complementarity Principle states that a quanton (a quantum system consisting of a Boson or Fermion) can either behave as a particle or as wave, but never simultaneosuly as both. A less orthodox interpretation of this Principle is the ``duality condition'' embodied in a mathematical inequality due to Englert [B-G Englert, Phys. Rev. Lett., Vol. 77, 2154 (1996)] which allows wave and particle attributes to co-exist, but postulates that a strong...

In a delayed-choice quantum eraser, interference fringes are obtained by erasing which-way information after the interfering particle has already been irreversibly detected. Following an introductory review of delayed-choice experiments and quantum erasure, we describe the experimental realization of an optical delayed-choice quantum eraser, suitable for advanced undergraduates, based on polarization-entangled pairs of single photons. In our experiment, the delay of the erasu...

We are developing a quantum interactive learning tutorial (QuILT) on a quantum eraser for students in upperlevel quantum mechanics. The QuILT exposes students to contemporary topics in quantum mechanics and uses a guided approach to learning. It adapts existing visualization tools to help students build physical intuition about quantum phenomena and strives to help them develop the ability to apply quantum principles in physical situations. The quantum eraser apparatus in the...

In a recent article Jan Sperling, Syamsundar De, Thomas Nitsche, Johannes Tiedau, Sonja Barkhofen, Benjamin Brecht, and Christine Silberhorn discuss the wave-particle duality using an experiment to demonstrate that "neither the wave nor the particle description is sufficient to predict the utcomes of quantum-optical experiments." I would like to draw your attention to two previous papers that discuss feasible experiments in which a photon does not seem to behave either as par...

We show that the first experiment with double-slits and twin photons detected in coincidence can be understood as a quantum eraser. The ``which path'' information is erased by transverse indistinguishability obtained by means of mode filtering in the twin conjugated beam. A delayed choice quantum eraser based on the same scheme is proposed.

The delayed-choice quantum eraser has been intensively studied for the wave-particle duality of a single photon in an interferometric system over the last decades. Coincidence measurements between quantum erasers have also been applied for the nonlocal quantum feature, satisfying the Bell inequality violation. However, those quantum features have not been clearly understood yet, resulting in the quantum mystery. Recently a coherence approach has been tried for the quantum era...

The delayed-choice thought experiment proposed by Wheeler has been demonstrated over the last several decades for the wave-particle duality of a single photon. The delayed-choice quantum eraser proposed by Scully and Druhl has also been intensively studied for the violation of the cause-effect relation of a single photon as well as a pair of entangled photons in an interferometric system. Here, a coherence interpretation is conducted for the nonlocal realism of the space-like...

It has often been remarked that single-photon interference experiments, however complicated, seem to behave very much in the same way as those performed in the classical regime, using the field generated by a laser. This observation has the status of being `well-known to those who know it', but perhaps mysterious to others. We discuss the reasons underlying the similarity and also some of the limitations of this simple idea.