HKUST Annual Report 2016-17

23 Quantifying Hydrophobic Interactions Hydrophobic interactions are a major type of intermolecular force that plays a vital role in many fundamental processes in chemistry and physics. Such interactions are intriguing as they exhibit a property called cooperativity, which does not exist in other fundamental intermolecular forces, such as dipole-dipole interactions and Van der Waals forces. To quantify hydrophobic interactions, Prof Xuhui Huang (Chemistry) and his collaborators carried out real-time monitoring of hydrophobic aggregation in bulk solution at the microsecond time scale by probing the fluorescence induced by hydrophobic aggregation and then fitting the measured fluorescence to kinetics nucleation- growth theory. The researchers discovered that cooperativity constitutes up to 40% of free energy formation in aggregation. The work was published in Nature Communications . Ocean Circulation, Ecosystem and Hypoxia around Hong Kong Waters Prof Jianping Gan (Mathematics, Environment and Sustainability) is leading a Theme-based Research Scheme “Diagnosis and prognosis of intensifying eutrophication, hypoxia and the ecosystem consequences around Hong Kong waters: coupled physical-biogeochemical-pollution studies” , which is funded $40 million by Research Grants Council from 2017- 2021. This project investigates holistically the coupled physical- biological-chemical processes in the interactive River-Estuary-Shelf system around Hong Kong waters through in situ field measurement, laboratory experiment and advanced numerical simulation. Their ultimate goal is to identify the factors driving the increasing eutrophication and hypoxia, and to provide analytical tools and a scientifically-based strategy for stabilizing or even reversing eutrophication and hypoxia and for ensuring the overall sustainability of the marine environment in Hong Kong. Moving Forward on Quantum Communication A large-scale atom-photon quantum network is still at the embryonic stage, limited by the interaction efficiency between atomic quantum nodes and flying single photons. To interact with atoms efficiently, the photons must have a bandwidth narrower than the atomic natural linewidth. In a world best, Prof Shengwang Du (Physics) and his group produced 2-MHz-linewidth biphotons from a Doppler-broadened (530 MHz) hot atomic vapor cell. The process is also simpler and costs less than the traditional cold atom system, bringing hope of further advancement for quantum communication and quantum information processing.