We present a new experiment, in which we measure quantum correlations between single photons that are mediated by the exchange of a single phonon. We create and annihilate a single optical phonon in bulk diamond using two ultrashort laser pulses at two different wavelengths, generated by a Ti:Sapph oscillator and a frequency-doubled optical parametric oscillator (APE Berlin). During Stokes Raman scattering, the first pulse creates a photon-phonon pair, while the second pulse convert the same phonon into an anti-Stokes photon. Using spectral filtering and photon counting, we measure the cross-correlations between the Stokes and anti-Stokes photons with a few hundred femtoseconds time resolution. As expected, the non-classical correlation (g(2) much larger than the classical bound) decays within a few picosecond, following to the dynamics of the phonon mode. Our results demonstrate a new source of broadly tunable quantum correlated photons, and can be extended to provide a new way of measuring non-classical dynamics in nanoscale systems — down to individual nanostructures.
When two sub-wavelength metallic nanoparticles, each of them supporting a resonant plasmon, are brought within few nanometers or less from each other, the two plasmonic resonances are strongly coupled. The new eigenmodes of the system include in particular a dipolar mode, for which the maximum electric field is localized in the nanoscale gap between the particles. The local field enhancement compared to the incoming far field can be several hundred folds.
We present the design and fabrication of such plasmonic gap cavities, created by depositing gold nanospheres on an atomically flat gold surface, which has been functionalized with a self-assembled monolayer of thiol molecules. This system enables extremely large and reproducible enhancement of the Raman signal from the molecules.
Although these nanogap cavities have been used in SERS studies for some time already, a detailed understanding of the out-of-equilibrium physics under laser irradiation is missing. What is the local temperature of the electrons in the metal? Is the molecular vibration in equilibrium with the surrounding thermal bath?
We will present our latest results in the spectroscopy of these nanocavities under broadly tunable excitation. In particular, we want to clarify if a suitable detuning of the laser from the plasmonic resonance can lead to amplification of molecular vibrations  well above the thermal occupancy.
 P. Roelli et al, Nature Nanotechnology 11, 164–169 (2016)
We have developed a CMOS-compatible Silicon-on-Insulator photonic platform featuring active components such as pi- n and photoconductive (MIM) Ge-on-Si detectors, p-i-n ring and Mach-Zehnder modulators, and traveling-wave modulators based on a p-n junction driven by an RF transmission line. We have characterized the yield and uniformity of the performance through automated cross-wafer testing, demonstrating that our process is reliable and scalable. The entire platform is capable of more than 40 GB/s data rate. Fabricated at the IME/A-STAR foundry in Singapore, it is available to the worldwide community through OpSIS, a successful multi-project wafer service based at the University of Delaware. After exposing the design, fabrication and performance of the most advanced platform components, we present our newest results obtained after the first public run. These include low loss passives (Y-junctions: 0.28 dB; waveguide crossings: 0.18 dB and cross-talk -41±2 dB; non-uniform grating couplers: 3.2±0.2 dB). All these components were tested across full 8” wafers and exhibited remarkable uniformity. The active devices were improved from the previous design kit to exhibit 3dB bandwidths ranging from 30 GHz (modulators) to 58 GHz (detectors). We also present new packaging services available to OpSIS users: vertical fiber coupling and edge coupling.