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arXiv:quant-ph/0107121

Restoration of Entanglement by Spectral Filters

Koji Usami, Yoshihiro Nambu, Satoshi Ishizaka, Tohya Hiroshima, Yoshiyuki Tsuda, Ken Matsumoto, Kazuo Torii Nakamura

Published Jul 24, 2001• 0 citations
arXivHTMLPDF

Abstract

We experimentally demonstrate that entanglement of bi-photon polarization state can be restored by spectral filters. This restoration procedure can be viewed as a new class of quantum eraser, which retrieves entanglement rather than just interference by manipulating an ancillary degree of freedom.
DOI
10.48550/arxiv.quant-ph/0107121

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Interaction with a measuring apparatus can cause otherwise interfering paths of a particle to become distinguishable. Under some conditions, however, it is possible to ``erase'' the distinguishability, thereby restoring interference. The concept of a quantum eraser is useful for understanding the role of entanglement in interference. Several attempts to investigate the phenomenon have been made using the correlated photons from spontaneous parametric down-conversion. However, none of the experiments previously performed in connection with quantum erasure has provided an optimal demonstration. We propose three improved down-conversion schemes, each of which satisfies all the criteria for a true quantum eraser. As the proposed schemes are all modifications or combinations of previously completed experiments, they are deemed to be feasible.