Einladung zum Promotionsvortrag von Frau Xiao-Liu Chu:
„Collecting photons with near-unity effiency using a dielectric antenna“
One efficient approach for generating single photons is based on using a two-level atom, which inherently cannot emit more than one photon at the time. As early as the 1980s, this quantum feature was identified as the gateway to creating single photon sources (SPS’s), where a regular excitation sequence would produce a stream of photons with photon number fluctuations below the shot noise.
Experimental realizations of such deterministic SPS’s have been hindered by large losses caused by low photon collection efficiencies and photophysical shortcomings. We investigated a planar metallo-dielectric antenna structure that is designed to convert the dipolar radiation of an arbitrarily oriented emitter to a directional beam with more than 99% efficiency.
We present the fabrication and characterization of such an antenna using a colloidal quantum dot as the single photon source, where we showed that it indeed directed the emission as expected. By further using a planar metallo-dielectric antenna applied to an organic molecule, we were able to demonstrate the most regular stream of single photons reported to date. We determined the sub-Poissonian nature of our SPS and showed that the intensity noise was reduced by 40% compared to the fluctuations of a shot-noise limited source of the same intensity. Such an ideal intensity squeezed SPS would be desirable for a range of applications, including quantum imaging, sensing, enhanced precision measurements and information processing. (Vortrag auf Englisch)
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