Detection of Sub-Shot-Noise Spatial Correlation in High-Gain Parametric Down Conversion

Università degli Studi dell'Insubria, Varese, Lombardy, Italy
Physical Review Letters (Impact Factor: 7.51). 01/2005; 93(24):243601. DOI: 10.1103/PhysRevLett.93.243601
Source: PubMed

ABSTRACT Using a 1 GW, 1 ps pump laser pulse in high-gain parametric down conversion allows us to detect sub-shot-noise spatial quantum correlation with up to 100 photoelectrons per mode by means of a high efficiency charge coupled device. The statistics is performed in single shot over independent spatial replica of the system. Evident quantum correlations were observed between symmetrical signal and idler spatial areas in the far field. In accordance with the predictions of numerical calculations, the observed transition from the quantum to the classical regime is interpreted as a consequence of the narrowing of the down-converted beams in the very high-gain regime.

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Available from: Ottavia Jedrkiewicz, Jul 30, 2015
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    • "In addition, macropixels of each beam known as coherence areas[27] are correlated pairwise across the beams, as shown in Fig. 1. In the limit that each coherence area could be described by a single spatial mode, and if each pair were isolated and the intensity difference measured , the quantum noise reduction would approach that of Eq. 2. A spatially resolving detector, such as a split photodiode, essentially performs this measurement when properly aligned. "
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    • "for realizing a set-up suited for a test of SSNQI, overcoming the limits of Ref. [24]. After eliminating with a prism the residual of first and second harmonic components, the pump beam crosses a spatial filter (a lens with a focal length of 50 cm and a diamond pin-hole, 250 µm of diameter), in order to eliminate the non-gaussian components and then it is collimated by a system of lenses to a diameter of w p = 1.25 mm. "
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