Harrie Massey Lecture

Prof Niek van Hulst (ICFO Barcelona) is visiting the UCL Physics Department today and giving the annual Harrie Massey Lecture on the topic of Coherent control of single molecules, complexes and nanoantennae.

Abstract: The observation of quantum mechanical effects in biological systems, such as light-harvesting antennae, has opened a lively debate as to the role of coherences in natural systems. Traditionally, such coherences are probed by manipulating quantum interference effects with shaped laser pulses. Yet the intrinsic structural inhomogeneity and environmental fluctuations of complex systems at ambient conditions average out most oscillatory spectroscopic features. Only by “single molecule detection” one can hope to catch a glimpse through the disorder. This lecture will present coherent control of single molecules, allowing both observation and manipulation of vibrational wave-packet interference and Rabi-oscillations in individual molecules at ambient conditions. The single-molecule approach ensures that the ultimate degree of coherent control can be realized. We have applied our novel method to single light-harvesting complexes and optical nanoantennas. Recent results on ultrafast quantum coherent energy transfer and femtosecond control of nanoscale hotspots will be presented.

Fano-Doppler Cooling paper

Our paper 'Fano-Doppler laser cooling of hybrid nanostructures' is now published in ACS Nano 5 7354-7361 (2011).

Laser cooling the center-of-mass motion of systems that exhibit Fano resonances is discussed. We find that cooling occurs for red or blue detuning of the laser frequency from resonance depending on the Fano factor associated with the resonance. The combination of the Doppler effect with the radiation cross-section quenching typical of quantum interference yields temperatures below the conventional Doppler limit. This scheme opens perspectives for controlling the motion of mesoscopic systems such as hybrid nanostructures at the quantum regime and the exploration of motional nonclassical states at the nanoscale.

Jeremy Baumberg seminar

Professor Jeremy Baumberg (Cambridge University) will be giving the CMMP/LCN seminar on NanoAssembly on the kilometre scale for NanoPhotonics, Wed 22 Jun 11

Abstract: New photonic properties are produced in materials which are assembled from diverse combinations of metals, semiconductors and dielectrics that are periodically structured on the 100nm-scale, with a wealth of potential applications ranging from communications to bio-sensing. However producing such nanomaterials on the mass-scale is far from trivial as three-dimensional structures are very hard for traditional lithography, and self-assembly has to date been a lab-scale tricky process.

Here we concentrate on a new range of structural colour nanomaterials which can be mass produced as films on the kilometre scale. While most man-made (and natural) colours exploit dye absorption, there is strong interest in avoiding these carcinogenic and UV-bleached chemicals. Alternative structural colours are produced from periodic wavelength-scale-sized transparent components, and thus are benign, long-lived, and possess new optical features. We create polymer photonics crystals made of cross-linked polymer spheres dispersed in a soft elastomeric matrix, using a novel industrially-scalable shear-based nano-assembly. Simply tuning the size of the spheres changes the colour across the entire visible spectrum, while optimised shearing creates single-domain opal films. Stretching these unusual elastomeric photonic crystals breaks their traditional optical scattering selection rules, and enables many applications. We demonstrate a wide variety of new optical properties based on the resonant scattering phenomena.

Nanophotonics meets quantum optics and NOIs meeting

This week Susan and Marios have been attending the 'Nanophotonics meets quantum optics' Physics School in Physikzentrum Bad Honnef, Germany, where they also presented a poster on some of our most recent work on nanofibre trapping.

On the last day of the Physics School the annual project meeting of our European project 'Nanofibre Optical Interfaces for Ions, Atoms and Molecules (NOIs)' was held, with progress reports from participants based in Cork, Moscow, London, Innsbruck and Mainz.