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Research in Optical Sciences

Two-Photon Spectral Amplitude of Entangled States Resolved in Separable Schmidt Modes

Marco Gramegna

Published Jan 1, 2014• 1 citation
Publisher

Abstract

Experimental realization of two-photon spectral amplitude engineering to produce a decomposition in non-overlapping Schmidt modes, each of which can be filtered losslessly. The method relies on spontaneous parametric down-conversion pumped by a comb-like spectrum radiation.
DOI
10.1364/hilas.2014.jw2a.45

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The full Schmidt decomposition of spatiotemporally entangled states generated from spontaneous parametric down-conversion (SPDC) has not been carried out until now due to the immense computational complexity arising from the large dimensionalities of the states. In this Letter, we utilize the rotational symmetry of the states to reduce the complexity by at least four orders of magnitude and carry out the decomposition to reveal the precise forms of the spatiotemporal Schmidt modes and the Schmidt spectrum spanning over 10^4 modes. We show that the Schmidt modes have a phase profile with a transverse spatial vortex structure that endows them with orbital angular momentum at all frequencies. In the high-gain regime, these Schmidt modes broaden and the Schmidt spectrum narrows with increasing pump strength. Our work can spur novel applications at the intersection of quantum imaging and spectroscopy that utilize entangled states produced from SPDC.