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Measuring non-linear functionals of quantum harmonic oscillator states

K. L. Pregnell
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Abstract

Using only linear interactions and a local parity measurement we show how entanglement can be detected between two harmonic oscillators. The scheme generalizes to measure both linear and non-linear functionals of an arbitrary oscillator state. This leads to many applications including purity tests, eigenvalue estimation, entropy and distance measures - all without the need for non-linear interactions or complete state reconstruction. Remarkably, experimental realization of the proposed scheme is already within the reach of current technology with linear optics.

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K. L. Pregnell. 2005-11-01. Measuring non-linear functionals of quantum harmonic oscillator states. https://doi.org/10.1103/physrevlett.96.060501

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