Invisible

In his laboratory in the Department of Physics of Complex Systems at the Weizmann Institute of Science, Prof. Leonhardt plans to investigate phenomena that range between the nanometer scale and those occurring in black holes.

According to Prof. Olaf Leonhardt, his research deals with historical and well-known topics: the connection between optics and curved space. We can grasp this connection instinctively, for example, when we observe a fish in a circular aquarium, and notice that its position changes when we look at it from different angles. The physical laws describing the bending of light when it passes through glass or water were defined by scientists as early as the beginning of the 17th century.

Despite all this, in 2006 Prof. Leonhardt surprised the world of science, when he published, at the same time as another group, articles describing how the principles of bending light rays can be applied to make objects invisible. Combining the findings of recent research in physics and ideas drawn from the design of new optical materials, he explained how it is possible to direct the light so that it travels in a circular manner, leaving an invisible "hole" in the center. "This way you can create a situation where the object appears to shrink to a point - and in practice it becomes invisible," he says.

Since the publication of the articles, several research groups around the world are trying to face the challenge of developing means to disappear from sight. The possibility of being completely invisible - to all wavelengths, and in three dimensions - is not yet practical, but some of those research groups have already succeeded in creating partial invisibility - for example, to the electromagnetic waves used in cell phones.

In his laboratory in the Department of Physics of Complex Systems at the Weizmann Institute of Science, Prof. Leonhardt plans to investigate phenomena that range between the nanometer scale and those occurring in black holes. For example, perfect visualization - the opposite of disappearing from sight - can also be based on the bending of light rays. Several years ago Prof. Leonhardt showed that it is possible to scatter the light rays and then focus them sharply, thus overcoming what is considered the fundamental limitation of light microscopy - the impossibility of seeing things smaller than the wavelength of visible light. So far he has been able to prove the finding with microwave rays, which have a longer wavelength, and his goal is to show that this is also possible in the fields of visible light. Possible applications for this could include methods for etching tiny, detailed prints on electronic chips.

The processes that take place in black holes are another subject that fascinates Prof. Leonhardt. Since black holes, by their nature, are not visible in our telescopes, and cannot be studied closely, he is developing methods that will make it possible to create simulations of black holes in the laboratory using light. He discovered that very short and very concentrated pulses of laser light in an optical fiber can mimic what happens in a black hole. Among other things, Prof. Leonhardt is preparing to use such systems to try to answer questions about the radiation that is believed to be emitted from black holes.

Another area he plans to investigate concerns quantum phenomena discovered in the late 40s: two metal plates placed a few micrometers apart, in a vacuum, will be attracted to each other, even though no visible force is acting on them. Prof. Leonhardt points out that examples of this phenomenon can be seen in everyday life: this is the reason why parking tickets remain "stuck" to the windshield. However, the physical laws underlying the phenomenon are not understood. Prof. Leonhardt plans not only to investigate what causes this attraction, but also how it can be influenced and even reverse the direction of its action. Findings in this field may be essential for the development of nanomachines: in such small dimensions, the attraction effect is a decisive factor, which considerably affects the movement of the machines.

Prof. Olaf Leonhardt came to the Weizmann Institute of Science from the University of St. Andrews in Scotland. Born in East Germany, he received a PhD in theoretical physics from Humboldt University, Berlin, in 1993. His scientific career has taken him to Oregon, Sweden, Germany, Singapore, Australia and China. He finally chose the Weizmann Institute of Science, because he was attracted to the open and supportive atmosphere he knew from previous visits. "I feel very welcome here, and I look forward to establishing my own research group, and also working with strong research groups in the field of optics, which operate at the institute," he says.