http://www.focus.technion.ac.il/May10/researchStory3.htm
| A quantum machine gun is not to be normally associated with a super-powerful new age of computers. But revolutionary ideas from Netanel Lindner - a PhD student at the Faculty of Physics - bring hopes of making the futuristic idea of a quantum computer a feasible reality. By Georgina Johnson   Netanel Lindner, PhD Computer power. It is a force that will decide the destiny of nations. We want more and we need more. A simple rule of computing is that the more you can increase the units of information, the more you will boost computing power. In quantum computing, raising the number of quantum bits, or qubits, has an even greater impact - as each qubit doubles the computing power. In order to be useful for quantum computing, the qubits need to be entangled - a property unique to quantum systems. Photons (quanta of light) are one of the most promising implementations of qubits. Unfortunately, existing methods of producing entangled photons tend to spew out photons more or less randomly. The most researchers have achieved to date, says PhD student Netanel Lindner, are six unpredictable, photonic qubits. But in 2009, Lindner and colleague Terry Rudolph from Imperial College London published in Physical Review Letters a blueprint for a system that fires out large numbers of entangled photons on demand - the “photonic cluster state machine gun.” At the design’s core is a quantum dot - a nanoscale crystal within a semiconducting device - chilled to a low temperature. When a short, strong pulse of light hits the dot, one of the electrons inside is raised to an excited state. As it “relaxes” back to its resting energy state, it throws out a photon. “We can manipulate the electron in such a way that it is entangled with the photon,” Rudolph said. Excite the same electron again and it spews out a second photon that is also entangled with the electron, and therefore with the first photon too. Repeat the process many times and a string of entangled photons emerges, ready to inject into a quantum computer. “This is a milestone towards building a quantum computer based on photons,” says Lindner. The original concept of a photonic machine-gun has had an explosive impact on world researchers. “It’s a superb piece of work,” said Andrew White at the University of Queensland in Brisbane, Australia. “I think this is one of the most exciting theoretical proposals I’ve read in five years - it will be a revolutionary advance for photonic quantum computing.” Most at home in consort with Technion’s hottest professors of physics, electrical engineering, computer science and mathematics, Lindner, who is now at the Institute of Quantum Information at the California Institute of Technology (Caltech), was a student of the late Distinguished Prof. Asher Peres. Peres was a student of Prof. Nathan Rosen, the last assistant of Albert Einstein - the founder of quantum physics. “I was a master’s student of Prof. Asher Peres - this was a unique experience,” says Lindner. “I learned about the foundations of Quantum Mechanics, Information Theory, General Relativity, and the interplay between these theories. He was a deep thinker and was very interested in the basic structure of theories.” “From my PhD supervisor, Prof. Assa Auerbach, I learned yet another perspective of theoretical physics,” continues the highly promising young scientist, “one which starts from inputs coming from experimental results.” “As a theoretical physicist, I need to explain theoretical ideas to experimentalists and at the same time understand the experimentalists’ issues, so that these ideas can still be put to work.” Lindner coauthored papers with both Prof. Joseph Avron, a mathematical physicist, and with Prof. David Gershoni, an experimentalist. In 2006, this collaboration led to a groundbreaking experiment, showing that a quantum dot can produce pairs of entangled photons. “It is great to be a bridge between the theoretical and the experimental,” he says. Lindner was in the Chais Family Foundation Gifted Students Program between 2001 and 2002 and he recommends to current participants that, “Research is more important than grades.” | |
