A symmetry analyser for non-destructive Bell state detection using weak nonlinearities

S.D. Barrett, Pieter Kok, Kae Nemoto, R.G. Beausoleil, W.J. Munro and T.P. Spiller

Physical Review A 71, 060302, Rapid Communication (2005)


We describe a novel method to project photonic two-qubit states onto the symmetric and antisymmetric subspaces of their Hilbert space. This device utilizes a weak cross-Kerr non-linearity, generated, for example, by electromagnetically induced transparency. The symmetry analyser is non-destructive, and works for small values of the cross-Kerr coupling. Furthermore, the device can be used to construct a quantum non-demolition Bell state analyser and detector.

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© 2017 Pieter Kok

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