Density matrix approach to the Heisenberg-limited interferometry: An example

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Conference Proceeding

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It has been known for a while that, provided by the Heisenberg Uncertainty Principle, certain types of quantum correlated light should yield a better scaling law than the one with ordinary laser light. Hitherto, however, there is no such device practically used outside laboratories. The fact that quantum correlations are easy to be destroyed under decoherencc essentially makes their utilities problematic for real world applications. For the optical interferometers, the most significant deeoherencc phenomenon is the photon loss. And yet, there has been no real-world device for quantum-enhanced sensing that overcomes the photon loss effects. In order to analyze the photon loss effects the description of the quantum states of light calls for a density matrix formalism, rather than the usual pure state approach. Here we take an example of the input states for the Heisenberg-limited interferometry, namely the optimal state, and show the description of the quantum state of light based on the reduced density matrix. © 2009 SPIE.

Publication Source (Journal or Book title)

Proceedings of SPIE - The International Society for Optical Engineering

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