Theoretical optics
Hello, you have reached the webpage of Ole Steuernagel.
I work mostly on theoretical optics.
I have just finished work on `Wigner flow'. This work, in collaboration with Dimitris Kakofengitis and Georg Ritter establishes the quantum analog of classical particle flow along phase portrait lines.
This is surprising since we know that Heisenberg's uncertainty principle precludes the existence of phase portrait lines since sharply defined trajectories are `not allowed'.
Our work reveals hidden features of quantum dynamics and extra complexity. Being constrained by conserved flow winding numbers, it also introduces topological order into quantum dynamics. For details see the preprint or download the pdf. If you are interested in further details still, see these (Large!~several Mb each) animations that illustrate topological charge conservation in the system we studied.
Recent work of mine investigates helices of light. Intensity helices of light that is. They can arise as an interference phenomenon. It turns out that threads of darkness, dark helices, fare better than bright ones. They are less constrained by optical resolution limits.
Dark helices are much more sharply defined than bright helices when you "see" them on a logarithmic scale, photo-resists tend to do just that. They are potentially more useful in laser tweezing arrangements since they are dark. This means less light is scattered when you trap a low field seeking particle. That may turn out be important for applications such as atom-trapping, trapping of molecules with handedness in solution, or bulk production of helical photo-lithographic imprints; to create metamaterials, say. For details see the article at Optics Express. Here is a link detailing some of the Media Echo.
I got started on classical wave optics when I tried to understand Gouy's phase which is known to render laser beams isomorphic to the wave description of quantum harmonic oscillators.
The animation shows the intensity inversion at the focus of a coherent laser beam due to the action of Gouy's phase. You can almost 'see' how wave optics gives rise to ray optics... In my wave optics work I explore effects in multimode laser beams: some of it has been verified experimentally (in collaboration with Miles Pagett's group).
In my quantum optics work I am mostly interested in fundamental limits of optics such as Afshar's paradox, which I helped to resolve. I am also interested in the limits of interferometry to determine path length differences, or the limits of interferometry for quantum imaging: this latter scheme has actually been implemented experimentally by Takeuchi's group and a very similar one by Zeilinger's group.
A related topic I was interested in is quantum lithography. I have shown that it can unfortunately not work because photons cannot be spatially concentrated, these considerations have been beautifully generalized by Tsang's work on limits for multi-photon absorption.
A link between my quantum and wave optics work is formed by work on atom optics. Recently, I developed an idea to create superpositions of laser beams in order to design a lens for atom beams with large numerical aperture arXiv:0810.4486v2 Phys. Rev. A (2009).
I also have an interest in complex systems, such as traffic and 'traffic' and biological systems (How to kill persistent bugs: arXiv:q-bio/0512003v1).
There has been some media interest in Daniel Polani's and my work on "How to kill persistent bugs": (officially it appeared in 10.1109/TEVC.2010.2040181). Here is a link detailing some of the Media Echo. I also got interviewed on the radio about it, listen to this: Nine_OClock_Show_Ronnie_Barbour__BBC_ThreeCountiesRadio.mp3.