Physics Colloquium, October 9, 2007
Mysteries of Quantum Entanglement: why cos2 α ≥ cos α for all values of α. J. H. Eberly

Department of Physics and Astronomy, University of Rochester

The invention of the two-photon Clauser interferometer opened a completely new domain of photon spectroscopy. It allowed direct experimental demonstration for the first time of non-local non-realist phenomena in physics. We will describe this interferometer, analyse its application to the detection of bi-photons, and prove the theorem in the title. Various phenomena at the interface between classical and quantum physics, e.g., Schrödinger's Cat, are related to it. An indirect consequence is that decay to steady state is not always what we were taught. Recent experiments on photons [1] and atoms [2] demonstrate the difference between local decay and non-local decay of entangled quantum systems that are coupled to independent environments. Even when decay of a system is locally smoothly asymptotic, non-local quantum entanglement may be non-smooth and disappear discontinuously. This "sudden death" constitutes yet another distinct and counterintuitive trait of entanglement, confirming earlier predictions [3,4].

Research reported here has been principally supported by NSF PHY-0601804 and ARO PH-48422.

[1] M. P. Almeida, F. de Melo, M. Hor-Meyll, A. Salles, S. P. Walborn, P. H. Souto Ribeiro, L. Davidovich, Science 316, 579 (2007)

[2] J. Laurat K. S. Choi, H. Deng, C. W. Chou and H. J. Kimble, arXiv: quant-ph 0706.0528.

[3] Ting Yu and J. H. Eberly, Phys. Rev. Lett. 93, 140404 (2004) and Phys. Rev. Lett. 97, 140403 (2006).

[4] J. H. Eberly and Ting Yu, Science 316, 555 (2007).

Dr. Eberly's Talk

Dr. Eberly's Web Site

4:00 p.m., Physics Research Building (PRB), Room 1080

Reception at 3:45 p.m., Atrium, PRB