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arXiv · quant-ph/0312048

Measuring a photonic qubit without destroying it

G. J. Pryde·J. L. O'Brien·A. G. White·S. D. Bartlett·T. C. Ralph
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Abstract

Measuring the polarisation of a single photon typically results in its destruction. We propose, demonstrate, and completely characterise a \emph{quantum non-demolition} (QND) scheme for realising such a measurement non-destructively. This scheme uses only linear optics and photo-detection of ancillary modes to induce a strong non-linearity at the single photon level, non-deterministically. We vary this QND measurement continuously into the weak regime, and use it to perform a non-destructive test of complementarity in quantum mechanics. Our scheme realises the most advanced general measurement of a qubit: it is non-destructive, can be made in any basis, and with arbitrary strength.

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G. J. Pryde, J. L. O'Brien, A. G. White, S. D. Bartlett, T. C. Ralph. 2003-12-05. Measuring a photonic qubit without destroying it. https://doi.org/10.1103/physrevlett.92.190402

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