Efficient interaction of light and matter at the ultimate limit of single photons and single emitters is of great interest from a fundamental point of view and for emerging applications in quantum engineering. However, the difficulty of generating single-photon streams with specific wavelengths, bandwidths, and power as well as the weak interaction probability of a single photon with an optical emitter pose a formidable challenge toward this goal. Here, we demonstrate a general approach based on the creation of single photons from a single emitter and their use for performing spectroscopy on a second emitter situated at a distance. While this first proof of principle realization uses organic molecules as emitters, the scheme is readily extendable to quantum dots and color centers. Our work ushers in a new line of experiments that provide access to the coherent and nonlinear couplings of few emitters and few propagating photons.

Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales.

We report angle-and momentum-resolved measurements of the dissociative ionization and Coulomb explosion of methyl halides (CH 3 F, CH 3 Cl, CH 3 Br, CH 3 I) in intense phase-controlled two-color laser fields. At moderate laser intensities we find that the emission asymmetry of low-energy CH + 3 fragments from the CH + 3 + X + (X = F,Cl,Br,I) channel reflects the asymmetry of the highest occupied molecular orbital of the neutral molecule with important contributions from the Stark effect. This asymmetry is correctly predicted by the weak-field asymptotic theory, provided that the Stark effect on the ionization potentials is calculated using a non-perturbative multi-electron approach. In the case of high laser intensities we observe a reversal of the emission asymmetries for high-energy CH + 3 fragments, originating from the dissociation of CH 3 X q+ with q ≥ 2. We propose ionization to electronically-excited states to be at the origin of the reversed asymmetries. We also report the measurements of the emission asymmetry of H + 3 which is found to be identical to that of the low-energy CH + 3 fragments measured at moderate laser intensities. All observed fragmentation channels are assigned with the help of CCSD(T) calculations. Our results provide a benchmark for theories of strong-field processes and demonstrate the importance of multi-electron effects in new aspects of the molecular response to intense laser fields.

We present a facile, broadly applicable method to prepare nanoporous silver films using soluble salt nanoparticles as pore templates. The fabrication starts by printing a silver/CaCO3 nanoparticle based ink onto a flexible substrate and removing the CaCO3 by washing in a weak acid. The membrane thickness and pore size can easily be tuned between 0.5−5 μm and 30−300 nm, respectively, by a simple pH or temperature treatment (sintering at 200 °C). As a conceptual demonstration of the resulting large-area, defect-free, and homogeneous microstructure, we use these membranes to efficiently filter aqueous dispersions of carbon nanoparticles (20 nm primary particle size) at a filtration efficiency of >99.6%.