Polarization effects in lattice-STED microscopy.

Massive parallelization of STED-like nanoscopies is now achievable using well-designed optical lattices for state depletion. Yet, only the lattice intensity distribution was considered for the description of the super-resolved point spread function. This holds for fast-rotating fluorescent emitters. Here, we study the effects of electric field topography in lattice-STED microscopy. The dependence of the super-resolved point spread function on the number of dipoles and their orientation is investigated. Single fluorescent nano-diamonds are imaged using different optical lattice configurations and the measured resolutions are compared to theoretical simulations.

Photon bunching in cathodoluminescence.

We have measured the second order correlation function [g^{(2)}(τ)] of the cathodoluminescence intensity resulting from the excitation by fast electrons of defect centers in wide band-gap semiconductor nanocrystals of diamond and hexagonal boron nitride. We show that the cathodoluminescence second order correlation function g^{(2)}(τ) of multiple defect centers is dominated by a large, nanosecond zero-delay bunching (g^{(2)}(0)>30), in stark contrast to their flat photoluminescence g^{(2)}(τ) function. We have developed a model showing that this bunching can be attributed to the synchronized emission from several defect centers excited by the same electron through the deexcitation of a bulk plasmon into few electron-hole pairs.

Direct measurement of the photon statistics of a triggered single photon source.

We studied intensity fluctuations of a single photon source relying on the pulsed excitation of the fluorescence of a single molecule at room temperature. We directly measured the Mandel parameter Q(T) over 4 orders of magnitude of observation time scale T by recording every photocount. On time scale of a few excitation periods, sub-Poissonian statistics is clearly observed and the probablility of two-photons events is 10 times smaller than Poissonian pulses. On longer times, blinking in the fluorescence, due to the molecular triplet state, produces an excess of noise.

Photon antibunching in the fluorescence of a single dye molecule embedded in a thin polymer film.

We used scanning confocal microscopy to study the fluorescence from a single terrylene molecule embedded in a thin polymer film of polymethyl methacrylate, at room temperature, with a high signal-to-background ratio. The photon-pair correlation function g((2))(tau) exhibits perfect photon antibunching at tau = 0 and a limit of 1.3, compatible with bunching associated with the molecular triplet state. Application of this molecular system to a triggered single-photon source based on single-molecule fluorescence is investigated.

Quantized atom-field force at the surface of a microsphere.

The dipole force experienced by an atom in a nonresonant spatially inhomogeneous light field is quantized by the discrete nature of the photon. We propose to detect this quantization by studying the scattering of slow atoms that pass in the evanescent field of a microsphere whispering gallery mode. This constitutes an inverse Stern-Gerlach experiment in which the atomic deflection is correlated to the state of the scattering field.