Room-temperature single photon sources with definite circular and linear polarizations

Optics and Spectroscopy (Impact Factor: 0.56). 01/2010; 108(3):417-424. DOI: 10.1134/S0030400X10030161

ABSTRACT We report experimental results of two room-temperature single photon sources with definite polarization based on emitters
embedded in either cholesteric or nematic liquid crystal hosts. In the first case, a cholesteric 1-D photonic bandgap microcavity
provides circular polarization of definite handedness of single photons from single colloidal semiconductor quantum dots (nanocrystals).
In these experiments, the spectral position of the quantum dot fluorescence maximum is at the bandedge of a photonic bandgap
structure. The host does not destroy fluorescence antibunching of single emitters. In the second case, photons with definite
linear polarization are obtained from single dye molecules doped in a planar-aligned nematic liquid crystal host. The combination
of sources with definite linear and circular polarization states of single photons can be used in a practical implementation
of the BB84 quantum key distribution protocol.

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