Decoherence in a double-slit quantum eraser

F. A. Torres-Ruiz, G. Lima, A. Delgado, S. Pádua and C. Saavedra
PHYSICAL REVIEW A 81, 4 (2010)

ABSTRACT

We study and experimentally implement a double-slit quantum eraser in the presence of a controlled decoherence mechanism. A two-photon state, produced in a spontaneous parametric down-conversion process, is prepared in a maximally entangled polarization state. A birefringent double slit is illuminated by one of the down-converted photons, and it acts as a single-photon two-qubits controlled-not gate that couples the polarization with the transversal momentum of these photons. The other photon, which acts as a which-path marker, is sent through a Mach-Zehnder-like interferometer. When the interferometer is partially unbalanced, it behaves as a controlled source of decoherence for polarization states of down-converted photons. We show the transition from wavelike to particle-like behavior of the signal photons crossing the double slit as a function of the decoherence parameter, which depends on the length path difference at the interferometer.

DOI: http://dx.doi.org/10.1103/PhysRevA.81.042104



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