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NEWS BRIEF Physicists Produce Photons Ideal for Quantum Networking Compiled by Zhao JingHua Advances in Photonics Around the World Physicists at the Max Planck Institute for Quantum Optics in Garching, Germany, have used a rubidium atom that was strongly coupled to a high-finesse optical cavity (above) to produce, on demand, a sequence of single photons with welldefined and identical properties. The photons are created by an adiabatically driven stimulated Raman transition between two atomic ground states. This process is performed in a unitary way and is therefore reversible, which the researchers say makes it ideal for sending and receiving single photon states within a quantum-computing network. The group described the process in the Aug. 5 issue of Physical Review Letters. Electrical pulses break light speed Pulses that travel faster than light have been sent over a significant distance for the first time. Alain Hache and Louis Poirier of the University of Moncton in Canada transmitted the pulses through a 120-metre cable made from a coaxial “photonic crystal”. To create their cable, the Canadian researchers joined together five-metre sections of coaxial cable with alternating electrical impedance. They sent electromagnetic pulses with frequencies between 5 and 15 MHz through the cable, and found that the group velocity reached 3 times the speed of light for frequencies in the absorption band. This was remarkable in comparison with many existing information systems that are based on coaxial cables with data speed of just two-thirds the speed of light. The achievement that utilized the backreflection caused by impedance mismatch raise hopes that data could travel through electronic communications systems at almost the speed of light. A Hache and L Poirier 2002 Appl. Phys. Lett. 80 518 A breakthrough in teleportation When physicists teleported photons for the first time in 1997, they had to destroy the photons to be sure that the teleportation had been successful. Now a team at the University of Vienna has managed to teleport photons without destroying them. Jian-Wei Pan and colleagues believe that their method could be the next step towards longdistance quantum communication. In a standard telepor- 28 hotonics'a tation experiment, a laser is directed at a crystal with nonlinear optical properties. Occasionally the photon will be “down-converted” into two lower energy photons, and sometimes these photons will have their polarizations entangled wherein one of them is vertically and the other horizontally polarised. By using a filter to reduce the intensity of the photons that are going to be teleported, the researchers were able to significantly reduce the number of spurious detection events. The Vienna team could be 97% certain that the state had been teleported to a photon without actually having to detect it. Such a high accuracy means that the teleported photons could be used in “quantum repeaters” for long distance communication. The team now hopes to combine these results with a technique known as entanglement purification to further develop quantum communication over long distances. (J -.W Pan et. al. ,Nature, 421 721, 2003). Laser takes up gene therapy Scientists in Germany have used a Ti:sapphire laser to transfer DNA into a cell. Femtosecond lasers improve the transfer of DNA into cells and could advance the fields of gene therapy and DNA vaccination, according to Uday Tirlapur and Karsten König of Friedrich Schiller University in Jena. U. Tirlapur and K. König, Nature, 418 290 See-Through Thin-Film Transistor Unveiled Transparent electronics may seem the stuff of science fiction, but engineers from Oregon State University and Hewlett-Packard Co. in Corvallis, Ore., have developed zinc-oxide-based thinfilm transistors that they hope will find applications in liquid crystal displays and elsewhere. They reported the devices, which display optical transmission in the visible portion of the electromagnetic spectrum of approximately 75 percent, in the Feb. 3 issue of Applied Physics Letters. The team fabricates the N-type semiconductor devices by depositing a layer of indium tin oxide and aluminium titanium oxide on a glass substrate. The zinc-oxide channel and indium-tin-oxide source and drain electrodes are subsequently added to the stack by ion-beam sputtering.
S tudent ACTIVITIES Making presentations work: National Lecture Competition Charles K. F. Ho 3rd price overall: Development of optical materials by the sol-gel process Competition Organizers: Institute of Minerals, Metals and Materials, UK and Institute of Materials, East Asia, Singapore Flashback: March 2003 – South-east Asia Regional Competition in NTU, Singapore. Now the Finals, London, UK Taking the london tube to the venue on the East End, I really felt that I could not have been more prepared (with all the first year presentation trials, onfig progress report and the regional qualifier presentation). Upon arrival, I found myself submerged in a crowd of academic and industry representatives from the world of material science. Like everyone else, I was overwhelmed by the unique ambience and the interior decoration of the building (see photos). It was full of medieval armour suits, which gave me shivers down my spine. Just can’t help the thought that these suits might be haunted by their owners. Furthermore, the Master of the Worshipful Company of Armourers and Brasiers (the main corporate sponsor and they make armours!), indicated that this very same building dates back all the way to the 1600s. It survived the ‘Great London Fire’ in 1666 and ‘The Blitz’ during wwii. This just helped to feed my imagination about these armours jumping down from the wall! With all the opening addresses, the finals officially kicked off with the first contestant taking the stage. Scrolling down the program, I found that I was the only oversea representative. So it was me versus the entire United Kingdom! WOW, it could be rough. Then I thought to myself with some pride...it did somewhat made sense for me to represent the overseas region as I was born in Hong Kong, studied in UK, moved to Canada and now studying in a Singapore University. These countries represent a good portion of the commonwealth! The presentations of the other finalists from different regions of the UK covered a broad spectrum of applications: biomaterials, instrumentation, composite materials, materials simulation, making of bells, etc. They were all entertaining and informative in their own way. Soon, it was my turn to educate the audience about materials in photonics. Taking a deep breath, I cracked a joke with the crowd, and I was 15 mins away from the hope that all my extravagant expenditure in London could be covered by the prize money. I started my timer...The presentation was so well rehearsed that I was actually finished with one minute to go! It took me about 10 seconds to bring myself to believe my stopwatch and another 10 to figure out what to say to make the most out of the remaining 40 s. And then I said my grace and took my next breath! After a delicious buffet dinner, the long awaited moment arrived. VIPs assembled on the stage. The announcement came with me taking the third place overall. Well, I really didn’t mind to hear my name a few more minutes later (when they announced the 2nd and NATIONAL LECTURE COMPETITION 2003 September 2003 29
Page 1 and 2: hotonics'a A Publication of the Pho
Page 3 and 4: My warmest greetings to all the stu
Page 5 and 6: Research Funding: Total cumulative
Page 7 and 8: Biophotonics Research Ast/P Ng Beng
Page 9 and 10: the laser active Q-switching techni
Page 11 and 12: Electrically tunable dispersion com
Page 13 and 14: Thermal characterization of GaAsN e
Page 15 and 16: Polymer Photonics Polymeric materia
Page 17 and 18: (b) Figure 1: (a) the selective are
Page 19 and 20: Low k material Porous dielectric ma
Page 21 and 22: Liquid Crystal Devices Ast/P Sun Xi
Page 23 and 24: Now let’s take a look at the phys
Page 25 and 26: FEATURE ARTICLE Optical Tweezers Le
Page 27: References [1] Ashkin, A., Dziedzic
Page 31 and 32: Congratulations to Hery Djie who de
Page 33 and 34: Announcements New Faces The Centre
Page 35 and 36: ZUGO PHOTONICS PTE LTD www.zugo.com

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